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35
votes
19answers
8k views

Getting the sequence $1, 0, -1, 0, 1, 0, -1, 0, \ldots$ without trig?

What's the simplest way to write a function that outputs the sequence: 1, 0, -1, 0, 1, 0, -1, 0, ... ... without using any trig functions? I was able to come up ...
18
votes
9answers
3k views

Is the Look and Say Sequence a “proper” maths problem? [closed]

I once told my brother about the "Look and Say Sequence" (i.e. 1, 11, 21, 1211, 111221, ...). My brother then showed the sequence to his maths teacher at school and asked him to predict the next ...
9
votes
7answers
2k views

Pattern to last three digits of power of $3$?

I'm wondering if there is a pattern to the last three digits of a a power of $3$? I need to find out the last three digits of $3^{27}$, without a calculator. I've tried to find a pattern but can not ...
9
votes
2answers
132 views

Has anyone noticed this pattern?

I've been messing around a bit and I noticed a curious pattern when it comes to progressions of powers. Let's take the progression of consecutive integers: $1,2,3,4,5,6,7,...$ Obviously it's an ...
9
votes
1answer
489 views

Are there “mental calculator” persons that can recognize closed-form expressions?

There are people, sometimes called mental calculators, who is capable of performing fast calculations in their head, involving multiplication, factorization, finding logarithms and roots of a high ...
7
votes
3answers
730 views

How to find pattern in $1,2,8,9,15,20,26,38…$ infinite sequence?

While I was investigating some specific types of prime numbers I have faced with the following infinite sequence : $1,2,8,9,15,20,26,38,45,65,112,244,303,393,560,....$ I tried to find recursive ...
7
votes
1answer
79 views

Finding $x^n$ patterns

I noticed the other day while computing consecutive powers of $2$ that for $n \geq 1$, the numbers in the ones place of the values of $2^n$ repeat every 4 terms $(2, 4, 8, 6,\ldots)$. In the tens ...
7
votes
1answer
190 views

What is the pattern or relation in this table?

Here is the table: $$\begin{array}{c} 0\\ 1\\ 1& 1\\ 3& 2& 3\\ 5& 3& 3& 5\\ 11 &8 &10 &8 &11\\ 21 &13 &14 &14 &13 &21\\ 43 ...
6
votes
1answer
305 views

How to Characterize Clumps in a Large, Semi-Random Graph

Consider large (100,000+ vertices, say) graphs, which we think of as representing some population with edges representing some form of symmetric relation. They might be the Friend graph of Facebook, ...
5
votes
2answers
279 views

Formula to this pattern?

I have this pattern: 1 11 21 1211 111221 I'm guessing it's a fibo pattern, been at it for hours now. Anyone know?
5
votes
2answers
198 views

Is This A Derivative?

I am in a little over my head. This all began with my reading how each level of pascals triangle adds to $2^n$, where n=row# starting with n=0. I then though, "wouldn't it be clever if the rows added ...
5
votes
0answers
125 views

Point Group of a pattern

I need to determine the point group of the following patterns: I think the one on the left is $D_1$ and the one on the right is $D_2$
4
votes
1answer
79 views

the table at the end of Theoretical Computer Science Cheat Sheet

Theoretical Computer Science Cheat Sheet, created by Steve Seiden, is a hodgepodge of well-known mathematical theorems and notions. I can understand (or guess at least) many of them, but I'm not sure ...
3
votes
3answers
535 views

Notation for factorial-type pattern with a skip/step of two instead of one?

I came across a peculiar pattern when solving a recurrence relation today: Some sequence $a_n$ looks as such: $a_0 = 1$ $a_2 = \frac{1}{2 \cdot 1}$ $a_4 = \frac{1}{4 \cdot 2 \cdot 1}$ $a_6 = ...
3
votes
1answer
574 views

Find the pattern, What is the correct answer

Ok, so this question is from seriously hard IQ test that has been doing the rounds on facebook, ok, 17 questions are easy 3 are hellishly hard, The answer to this one is 17, I do not know why, I ...
3
votes
1answer
142 views

What is the Galois group of $x^n + (x-1)^n $?

What is the Galois group of $x^n + (x-1)^n $ over the rationals in terms of the integer $n$ ? In case that is too hard , what is it for the first 20 integers ?
3
votes
3answers
129 views

Largest number on multiplying with itself gives the same number as last digits of the product

What is the largest number on multiplying with itself gives the same number as last digits of the product? i.e., $(376 \times 376) = 141376$ i.e., $(25\times 25) = 625$ If the largest number cant ...
3
votes
2answers
64 views

Recognize a valid binary Golay codeword

Are there any properties of a binary [24,12,8] Golay code which would allow me to say, for example, that a given 24-bit word is or is not a Golay codeword for some generator matrix? That is to say, is ...
3
votes
1answer
49 views

Get N value of this pattern (Triangular Number)

I have numbers formatted into this pattern. $$ ...
3
votes
1answer
92 views

Some questions about $\gcd(n,m)$ and $\phi(n)$

I was messing around in Excel at the end of work today and made a table where the $(i,j)$ entry $a_{i,j}$, for $j \geq i$, is 1 exactly when $i$ and $j$ are coprime (see snapshot of a portion of the ...
3
votes
1answer
71 views

finding all pairs $(x,z)$

How to find all pairs $(x,z)$ of integers for which $2(z+1)^3$ is divisible by $xz-1$
3
votes
3answers
188 views

Using Correlation for mouse gesture recognition

I am in need to build a mouse gesture recognition system which will compare given recognition to the the gestures in training data and will say where a given gesture best fits. I am planning to use ...
3
votes
0answers
80 views

Guilloché security printing — can it be cracked?

Money uses Security printing, and often uses Guilloché patterns. These curves are inscribed by wheels on wheels on wheels, ten wheels deep in some cases. For example, the back of the US $1 bill has ...
3
votes
0answers
199 views

Pattern puzzle help

I've spent hours on this puzzle, which shouldn't be too hard, and I'm sure I've got the right answer, but apparently it's wrong. The problem statement: You are guessing a positive number X. You ...
3
votes
0answers
289 views

What does this say about prime numbers?

I was having fun with Sage when I noticed something interesting: ...
2
votes
2answers
85 views

Finding pattern- $6$ $11$ $25$

Finding pattern$$ \begin{matrix} 6 & 11 & (25) \\ 8 & 6 & (16) \\ 12 & 5 & (?) \\ \end{matrix} $$ Options are : $10/12/14/16$ My ...
2
votes
1answer
111 views

Mathematical formula for a pattern

I was cooking and saw a chart of temperature vs cooking time like so: $154\mathrm{F}$ - $36$ hours $164\mathrm{F}$ - $18$ hours $174\mathrm{F}$ - $9$ hours Basically for every $10\mathrm{F}$ ...
2
votes
2answers
46 views

What is the relation between this binary number with no two 1 side by side and fibonacci sequence?

I saw this pattern of binary numbers with constraints first number should be 1 , and two 1's cannot be side by side. Now as an example ...
2
votes
2answers
1k views

Finding formula for the nth partial sum

A few days ago, I asked for some clarification about pattern recognition and the n-th partial sum for infinite series. Although the explanation given was top-notch (thanks again), I'm still having ...
2
votes
1answer
285 views

Function for number patterns

I'm primarily a programmer and am pretty rusty at math... so forgive me if this is a stupid question. I have four number patterns as follows: a) 3, 13, 31 b) 5, 17, 37 c) 7, 21, 43 d) 9, 25, 49 ...
2
votes
1answer
124 views

Mathematical Background for Computer Vision

I am a PhD student and would like to do deep research in the area of computer vision and pattern recognition. I know to be successful I need strong mathematical background. Could you please introduce ...
2
votes
1answer
179 views

Pattern of (1201, 2121, 3142, 4253, 5342)

What could be a part of the following set of numbers: $1201, 2121, 3142, 4253, 5342$ $a) 1317$ $b) 2315$ $c) 2573$ $d) 3456$ Differences between the numbers are $920, 1021, ...
2
votes
1answer
91 views

Pattern finding for repeating sequences

Find a pattern for the following sequence. 1,1,3,1,3,5,7,1,3,5,7..... Let n= the nth number. Find the nth number of this series
2
votes
3answers
151 views

Find Pattern of Numbers

I need some help figuring out a pattern. I have a set of numbers that are dependent on four variables i,j,k, and l. The combination of variables in one set leads to different values in another set. ...
2
votes
1answer
69 views

Order a list of sets based on a rule (pretty tough)

I did not know where to turn so I'm looking up anyone who could offer an answer to this interesting problem. I have a set of variables, listed as (A, B, C, D, E, F, G, H) Each variable is couple in ...
2
votes
1answer
87 views

Calculation for absolute value pattern

I have a weird pattern I have to calculate and I don't quite know how to describe it, so my apologies if this is a duplicate somewhere.. I want to solve this pattern mathematically. When I have an ...
2
votes
1answer
320 views

Bottom to top explanation of the Mahanalobis distance?

I'm studying Pattern recognition and statistics and almost every book I open on the subject I bump into the concept of Mahanalobis distance. The books give sort of intuitive explanations, but still ...
2
votes
1answer
124 views

How to calculate smallest pattern size based on set of ratios

So I have x number of items, each one has its own appearance ratio for making a pattern, of which I'm trying to determine the smallest possible pattern. The appearance ratios for all items total up to ...
2
votes
2answers
285 views

Pattern matching circle, square or triangle

I have a set of x, y co-ordinates that are actually taken from hand drawings of a circle, square or a triangle. Using the set of points, I need to mathematically find if the points approximately fit a ...
2
votes
1answer
111 views

How can one classify (match within a certain confidence interval) gestures based on accelerometer readings?

I am using an accelerometer-enabled device (mobile phone, to be specific) that enables sampling acceleration at a rate of about 20 samples per second. The samples contain three values, each ...
2
votes
0answers
105 views

Multiplication structure for finite abelian rings of order $p^2$.

Consider an odd prime $p$ and a positive integer $a$ as close to 2 as possible that is not a quadratic residue $mod$ $p$. If we extend the ring $mod$ $p$ with the element $b = a^{\frac{1}{2}}$ then ...
2
votes
1answer
181 views

What kind of recursion or series is this?

I am developing a language learning program, and would like to know the mathematical expression and description for what I have (perhaps incorrectly) calling a recursive series method of learning the ...
2
votes
0answers
68 views

Algorithm to predict next 3D points

For example, having this data: year x/y/z 2007 10/20/70 2008 20/10/70 2009 30/10/60 2010 40/10/50 2011 40/15/45 We want to predict what will be the x/y/z in ...
2
votes
1answer
98 views

Selecting and Grouping a set of points in a 2D plane

I am currently working on a project that requires to solve the following problem: Let's say that each time a user access a specific resource on the network from his mobile device, a system stores his ...
1
vote
2answers
202 views

In simple terms what is the sequence 220,171700,167167000,166716670000 a part of?

I know that <1,2,3,...,10>$\cdot$<1 0,9,8,...1>=220 <1,2,3,...,100>$\cdot$<100,99,98,...,1>=171700 <1,2,3,...,1000>$\cdot$<1000,999,998,...,1>=167167000 ...
1
vote
4answers
97 views

Finding $n^{th}$ term of sequence

$$3,8,17,32,57,\ldots$$ How do we find the $n^{th}$ term? I have been roaming aimlessly for a few minutes now. A definite pattern is in the differences of differences. Hints will be apreciated.
1
vote
1answer
142 views

Is there a pattern in figures whose perimeter is the same as their area?

Here's what I've found so far. Circumference of a circle with identical circumference and area: $4\pi$ Side length of a triangle with identical perimeter and area: $4\sqrt{3}$ And so on... ...
1
vote
2answers
157 views

Learning patterns and the maths

I am interested in learning more about patterns. My objective is to learn about how to analyse a set of numbers (not infinite but a large set of numbers in sequence) and see the patterns and then ...
1
vote
3answers
951 views

What is the next picture in this sequence?

I was reading a book on logical reasoning and came across the following: Can anyone give me the answer to the question. We want the next sequence ?
1
vote
2answers
654 views

How to find the pattern?

I'm challenging myself to figure out the mathematical expression of the number of possible combinations for certain parameters, and frankly I have no idea how. The rules are these: Take numbers ...