Questions on the Fibonacci numbers, a special sequence of integers that satisfy the recurrence $F_n=F_{n-1}+F_{n-2}$ with the initial conditions $F_0=0$ and $F_1=1$.

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2answers
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Domino tiling extended in N dimensions.

The standard domino tiling problem, is the number of ways to tile a board of size 2xn by dominos of size 2x1. The answer directly follows a recursion, the same as the Fibonacci series. If I extend ...
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1answer
31 views

Is there some function which return probability to select prime number from $n$ first Fibonacci numbers.

So my question is: is there function return probability to select prime number from $n$ first Fibonacci numbers. So maybe it realize with $\pi(n)$ function?
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1answer
36 views

How is this identity for Fibonacci numbers called?

In the course of proving another identity, I've found that $$F_n \equiv F_kF_{n-k+1} + F_{k-1}F_{n-k}$$ …for all corresponding n and ...
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2answers
147 views

Show that for a given $s$ there are a finite number of Fibonacci number of form $n^2+s$

It is well known that the last Fibonacci number $F_k$ such that $\exists \ n \in \Bbb{N} : F_k = n^2$ is $144$. Thus there are only $4$ perfect squares among the Fibonacci sequence (assuming you ...
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2answers
179 views

How to find a formula relating fibonacci sequence?

By shifting property of fibonacci numbers, $$F_{m+n} = F_m · F_{n+1} + F_{m-1} · F_n$$ where $F_k$ denotes the kth Fibonacci number . I want to extend it to some n numbers . So , how to find a ...
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4answers
107 views

Fibonacci inequality

If $F_n$ denotes the $n$-th Fibonacci number ($F_0 = 0, F_1 = 1, F_{n+2} = F_{n+1} + F_n$), show that the inequalities $F_{2n-2} < F_n^2 < F_{2n-1}$ hold for all $n ≥ 3$.
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1answer
1k views

Exponential lower bound for Fibonacci numbers

Can someone show me how to solve through induction, $F(N) \geq (3/2)^N$ for all $N\geq N_0$, where $F(n)$ is the Fibonacci function and $N_0$ is some positive integer. I know that $N_0$ should be $11$,...
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1answer
41 views

Is it rational or not?

I have two interesting question : Is this number rational or not: $$0.F_{1}F_{2}F_{3}...$$, where $F_{i}$ - Fibonacci number. And is this number rational or not: $$0.p_{1}p_{2}...$$
59
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3answers
696 views

Closed form solution for $\sum_{n=1}^\infty\frac{1}{1+\frac{n^2}{1+\frac{1}{\stackrel{\ddots}{1+\frac{1}{1+n^2}}}}}$.

Let $$ \text{S}_k = \sum_{n=1}^\infty\cfrac{1}{1+\cfrac{n^2}{1+\cfrac{1}{\ddots1+\cfrac{1}{1+n^2}}}},\quad\text{$k$ rows in the continued fraction} $$ So for example, the terms of the sum $\text{S}_6$ ...
9
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2answers
277 views

A number $N$ is a $k$-nacci number if and only if …

For $k\ge 2\in\mathbb N$, one can define the $n$-th $k$-nacci number $f_k(n)\ (n=0,1,\cdots)$ as $$f_k(0)=f_k(1)=\cdots=f_{k}(k-2)=0,\ \ f_{k}(k-1)=1,$$$$f_{k}(n+k)=f_{k}(n)+f_k(n+1)+\cdots+f_{k}(n+k-...
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2answers
70 views

Seeking a combinatorial proof $F_{mn}$ always a multiple of $F_m$

I would appreciate if somebody could help me with the following problem Q: Let $F_n$ the sequence of Fibonacci numbers, given by $F_1 = 1, F_2 = 1$ and $F_n = F_{n-1} + F_{n-2}$ for $n \geq 2$ ...
5
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2answers
76 views

Find $\mathrm{lcm}(F_{m},F_{n},F_{k})$.

So consider three Fibonacci numbers. My question is: Find $\mathrm{lcm}(F_{m},F_{n},F_{k})$, where lcm is least common multiple.
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0answers
28 views

Is the “Fibonacci square tiling” of Fibonacci-sided rectangles always optimal?

Is an optimal square tiling of a rectangle with side lengths of successive Fibonacci numbers always the sequence of Fibonacci numbers, as in the picture below?
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0answers
112 views

Can I use the equality $\phi^2=\phi+1$ without proving it?

I am looking at the following exercise: Show with induction, that the $i^{\rm th}$ Fibonacci number satisfies the equality: $$F_i=\frac{\phi^i-\hat{\phi}^i}{\sqrt{5}}$$ where $\phi$ ...
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5answers
8k views

Why does the Fibonacci Series start with 0, 1?

The Fibonacci Series is based on the principle that the succeeding number is the sum of the previous two numbers. Then how is it logical to start with a 0? Shouldn't it start with 1 directly?
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2answers
907 views

Is there among first $100000001$ Fibonacci numbers one that ends with $0000$?

This looks like a difficult problem: Is there among first $100000001$ Fibonacci numbers one that ends with $0000$? (it is from a competition training; trainer suggests using pigeonhole ...
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1answer
61 views

Convergence of Fibonacci quotients

Let $F_n=F_{n-1}+F_{n-2},~ F_0=0,~F_1=1~$ be the Fibonacci numbers. Then it is well known that $\lim_n \frac{F_{n+1}}{F_n}=\frac{1+\sqrt{5}}{2}$. However, many textbooks proved the above by using ...
2
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1answer
47 views

Fibonacci identity $F_{n+1}^2 - (F_{n+1}F_n) - F_n^2 = (-1)^n$

I am trying to prove Let $F_n$ be the $n$th Fibonacci number. Then $F_{n+1}^2 - F_{n+1}F_n - F_n^2 = (-1)^n$ I am not sure where to start with this.
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2answers
26 views

If $y_n = 2x_n-1$, show that $y_{n+1} = y_n + y_{n-1} + 1$

If $y_n = 2x_n-1$, how do you show $y_{n+1} = y_n + y_{n-1} + 1$ with $y_0 = 1$ and $y_1 = 1$? Would you start with $y_{n+1} = y_n + y_{n-1} + 1$, find a formula for $y_n$ and then compare it with $...
0
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1answer
49 views

How do you show $s_n = \frac{x_{n+1}}{x_n}$ where $(x_n)$ is the Fibonacci sequence?

Let $(s_n)$ denote the sequence satisfying: $s_{n+1} = 1 + \frac{1}{s_n}$ with $s_0 = 1$. Let $(x_n)$ denote the Fibonacci sequence and $x_n = \frac{5 + \sqrt{5}}{10}(\frac{1 + \sqrt{5}}{2})^n + \...
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1answer
66 views

Limit as $n \to \infty$ of $\frac{x_{n+1}}{x_n}$ in the Fibonacci sequence

Given that $x_n = \frac{\sqrt{5}+5}{10} (\frac{1 + \sqrt{5}}{2})^n + \frac{5 - \sqrt{5}}{10}(\frac{1 - \sqrt{5}}{2})^n$ How do you show that $\lim_{n \to \infty} \frac{x_{n+1}}{x_n}$ is the ...
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1answer
61 views

formula for the nth term of this sequence?

How do you find a formula for the nth term of this sequence? given that $x_n$$_+$$_1$ = $x_n$ + $x_n$$_-$$_1$ (Fibonacci sequence) and $x_0 = 1$ and $x_1 = 1$. Do i complete the square on $x^2 - x - ...
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2answers
42 views

Finding the limit of the following series, wherever it is convergent

Let $ f(x) = \sum_{n=1}^{\infty}a_nx^n $ where $a_n$ is the nth Fibonacci number. Find the values for which the series is convergent, and find $f(x)$ for those values. (i.e - find the limit when ...
5
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1answer
69 views

Limit of a specific sequence involving Fibonacci numbers.

Let, $\left\{F_n\right\}_{n=1}^\infty$ be the Fibonacci sequence, i.e, $F_1=1, F_2=1~\&~ F_{n+2}=F_{n+1}+F_n~\forall ~n \in \mathbb{Z}_+$ Let, $P_1=0, P_2=1$. Divide the line segment $\overline{...
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2answers
47 views

Proof concerning Fibonacci and recursively defined sequences

The series $(a_n)_{n\in\mathbb{N}}$ is given through $$a_1=1,\quad a_2=\frac{1}{2},\quad a_{n+2}=a_na_{n+1} \quad\text{ for } n\geq1.$$ I want to show that $$a_n = 2^{-f_{n-1}}$$ whereas $\,f_n$ ...
6
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1answer
95 views

Integral representation for Fibonacci's numbers

We know that, for example, the Gamma function is a perfect integral representation for the factorial $n!$ for a natural number $n$. $$\Gamma[n] = \int_0^{+\infty} t^{n-1}e^{-t}\text{d}t = (n-1)!$$ ...
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0answers
135 views

Is there a proven way to calculate the entry point(first occurence) of a factor m, in the Fibonacci sequence?

I saw a comment at the OEIS website for the sequence of entry points, of Fibonacci factors. https://oeis.org/A001177 It referenced a paper by Mark Renault in 1996, with the quote from OEIS: http://...
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2answers
53 views

Do I need induction here?

I am asked to prove, by using induction that $$\sum\limits_{i=1}^n F(2i-1) = F(2n)$$ for all real numbers n where the function F(i) gives the i:th fibonacci number. The series stars off with $F(0) =...
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4answers
141 views

Proving that $\binom{n}{0}+\binom{n-1}{1}+\binom{n-2}{2}+\cdots =F_{n+1}$ where $F_{n+1}$ is the $n+1$ th Fibonacci number [duplicate]

I have to proove this this identity which connects Fibonacci sequence and Pascal's triangle: $$\begin{pmatrix}n\\0\end{pmatrix}+\begin{pmatrix}n-1\\1\end{pmatrix}+\dotsm+\begin{pmatrix}n-\lfloor\frac{...
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2answers
46 views

How to prove this sequence is null?

I am working on the fibonacci numbers series using the ratio. To prove convergence I want to show that the sequence of the series is going to 0. And then according to the Leibniz criterion the series ...
3
votes
1answer
59 views

Convergence of Series Whose Terms are Defined Recursively

My recursively defined sequence $(a_n)_{n\in\mathbb{N}}$ is given trough $$a_1 = 1, \quad a_2=\frac{1}{2}\quad a_{n+2}=a_{n}a_{n+1}\quad \text{for } n\geq1$$ and I have to show that the series $$\...
0
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2answers
24 views

Closed form expression for zero of recurrence relation

Given the recurrence $d(i+1)=xFib(2i+1)-nFib(2i)$, where $Fib$ denotes the Fibonacci sequence (i.e. $Fib(0)=0, Fib(1)=1, Fib(2)=1, Fib(3)=2$, etc) and $n$ and $x$ are arbitrary integers, is it ...
0
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2answers
51 views

Convergence of Binet's formula expression for Fibonacci

Let $\displaystyle \phi = \frac{1+\sqrt{5}}{2}$ and $\displaystyle \psi = \frac{1-\sqrt{5}}{2}$. Consider the Fibonacci sequence defined by: $$ \displaystyle a_n = \frac{\phi^n - \psi^n}{\sqrt{5}} $$ ...
3
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3answers
117 views

Cesaro identity for Fibonacci numbers

I am stuck with the identity $$ F_{2n} = \sum_{k=1}^n \binom{n}{k} F_k, $$ which happens to be formula 80. I am using induction, but so far without too much result. $$ \sum_{k=1}^{n+1} \binom{n+1}{...
3
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0answers
37 views

Fibonacci numbers and binomial theroem [duplicate]

So I am trying to prove $$\sum_{i=0}^n{nCi×F_i} = F_{2n}$$ Such that $$nCi = \frac {n!}{i!×(n-i)!}$$ And $F_i$ is the ith value of the fibonacci sequence such that $F_0 = 1$ and $F_1 = 1$ I have ...
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5answers
2k views

Why is 11 times the 7th term of a fibonacci series equal to the sum of 10 terms?

Why is 11 times the 7th term of a fibonacci series equal to the sum of 10 terms? I was watching scam-school on youtube the other day and this number trick just astonished me. Can someone please ...
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1answer
60 views

Proof: Fibonacci Sequence (2 parts)

Part a) Prove or Disprove: There are only finitely many even Fibonacci numbers. I think I want to disprove this, as I know that every 3rd Fibonacci number is even, and thus there will be infinitely ...
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4answers
3k views

Show that $f(2n)= f(n+1)^2 - f(n-1)^2$

Let $f(n)=f(n-1)+f(n-2)$ be the Fibonacci sequence with $f(0)=0,f(1)=1$. Show that $$f(2n)= f(n+1)^2 - f(n-1)^2.$$ I have tried several different approaches to this problem. Both inducting from the ...
4
votes
5answers
781 views

Proof by induction: $n$th Fibonacci number is at most $ 2^n$

I'm trying to find the proof by induction of the following claim: For all $n\in\mathbb N$, $\operatorname{fibonacci}(n) \le 2^n$ My Proof: Base case: $n = 1$ $\operatorname{fibonacci}(1) \le 2^ 1$ ...
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1answer
55 views

How many times can $p$ divide $F_n$?

Given a prime $p$ and a number $n$ (or perhaps just an upper bound $x$ with some unknown $n\le x$), trivially one has $$ \operatorname{ord}_p F_n\le\frac{\log F_n}{\log p}\approx\frac{n\log\varphi}{\...
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0answers
31 views

Divisibility of Fibonacci Sequence mod prime

I have to solve the following problem and I have a few questions: Consider the Fibonacci sequence defined as $F_n:=2F_{n-1}+F_{n-2}$ with $F_0=1$ and $F_1=1$. Now, I need to prove that for any odd ...
16
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4answers
2k views

Converting recursive equations into matrices

How do we convert recursive equations into matrix forms? For instance, consider this recursive equation(Fibonacci Series): $$F_n = F_{n-1} + F_{n-2}$$ And it comes out to be that the following that ...
4
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1answer
341 views

Given Two Fibonacci numbers, predicting the median Fibonacci number

Wolfram Alpha gives the $100$th fibonacci number to be $354224848179261915075$ and the $104$th fibonacci number to be $2427893228399975082453$. Just from this, can we deduce what the $102$th fibonacci ...
2
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2answers
37 views

Sum of Squares for Odd Fibonacci Numbers

I am trying to prove the following theorem by induction: THEOREM: For the Fibonacci sequence $F_1$, $F_2$, ... , $F_n$ defined as, $F_1$ = $F_2$ = 1 $F_n$ = $F_{n-1}$ + $F_{n-2}$ for n >= 3, For ...
3
votes
1answer
117 views

Proving that every integer has a Fibonacci number multiple

Show that for any positive integer, there exists a Fibonacci number N such that N is divisible by the integer. I'm not really sure how to begin my approach to this problem, would really appreciate ...
0
votes
2answers
107 views

How find this value $m^2-mn-n^2$

let $$1+\dfrac{1}{1+\dfrac{1}{1+\dfrac{1}{1+\dfrac{1}{1+\cdots\dfrac{1}{1}}}}}=\dfrac{m}{n}$$ where $m,n$ are positive integer numbers,and such $gcd(m,n)=1$.,and article $1998$ the fractional ...
1
vote
3answers
85 views

Trying to prove $\sum_{i=1}^{N-2} F_i = F_N -2$

I'm trying to prove that $\sum_{i=1}^{N-2} F_i = F_N -2$. I was able to show the base case for when $N=3$ that it was true. Then for the inductive step I did: Assume $\sum_{i=1}^{N-2} F_i = F_N -2$ ...
4
votes
1answer
62 views

If $\frac{p_{n+1}}{np_n} \to p > 0 $, then $\sqrt[n+1]{p_{n+1}}-\sqrt[n]{p_{n}} \to \frac{p}{e}$

Problem: Prove that, if a sequence ${p_n}$ satisfies $p_n > 0$ and $\lim\limits_{n \to \infty} \frac{p_{n+1}}{np_n} = p > 0 $, then $\lim\limits_{n \to \infty} \left(\sqrt[n+1]{p_{n+1}}-\sqrt[n]{...
8
votes
2answers
341 views

Fiboncacci theorem: Proof by induction that $F_{n} \cdot F_{n+1} - F_{n-2}\cdot F_{n-1}=F_{2n-1}$

I have the following theorem to prove by induction: $$ F_{n} \cdot F_{n+1} - F_{n-2}\cdot F_{n-1}=F_{2n-1} $$ It is mentioned in my script that the proof should be possible only by using the ...
2
votes
2answers
552 views

Proving that for Fibonacci numbers $a_n \lt (\frac {1 + \sqrt 5} 2)^n$ for $n \ge 1$

I'd like to prove that for Fibonacci numbers $a_n \lt \left(\frac {1 + \sqrt 5} 2\right)^n$ for $n \ge 1$. I suppose it needs induction so, after verifying the trivial case $n=1$, the inductive step ...