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Lopsy
  • Member for 12 years, 2 months
  • Last seen more than a week ago
36 votes
Accepted

Show that the sequence $1,2,3,4,5,6,7,8,9,1,0,1,1,1,2,1,3,1,4,1,5,1,6,1,7,1,8,1,9,2,0,2,1,\cdots$ isn't periodic

35 votes
Accepted

Can a row of five equilateral triangles tile a big equilateral triangle?

25 votes

Proving $\sum_{k=0}^n(-1)^k\binom nk=0$

23 votes
Accepted

What is the significance of the power of $3$ in the sequence of primes given by $\lfloor A^{3^n}\rfloor ?$

15 votes

What are the theorems in mathematics which can be proved using completely different ideas?

15 votes

Longest known sequence of identical consecutive Collatz sequence lengths?

15 votes
Accepted

Find all polynomials that fix $\mathbb Q$ and the irrationals

13 votes

Unusual mathematical terms

12 votes
Accepted

Finding the GCD of three numbers?

10 votes
Accepted

Simple proof that stationary birth-death chains are reversible

9 votes
Accepted

Partitions of $\{1,\dots,n\}$ with no consecutive integers in each block is counted by $B(n-1)$?

9 votes

What is the problem in this solution to the Two Child Problem?

9 votes
Accepted

If a finite set of rational numbers sums to one, does one of the rationals have a denominator equal to the LCM of all the denominators?

8 votes
Accepted

Remember trig identities like $\cos(\pi/3) = 1/2$

8 votes

Graph on the cover of Bollobás's "Combinatorics"

7 votes
Accepted

Regular hexagon on a colored sphere

7 votes
Accepted

Inequality $a^2+b^2+c^2 \leq a^2b+b^2c+c^2a+1. $

6 votes
Accepted

Controlling the coefficients of the factors of a polynomial with integer coefficients

5 votes

probability unordered sample

4 votes
Accepted

Number of ways to assign numbers $1,2,\ldots, n$ to $x$ red balls and $y$ blue balls, $x+y = n$, in a set of $X$ red and $Y$ blue.

4 votes
Accepted

$\ell_p$ space for $p<1$

4 votes
Accepted

Contest problem on domain and range of square root function

4 votes
Accepted

Congruence question

3 votes
Accepted

Finding the least significant digit of a large exponential.

3 votes
Accepted

How do I write this simple proof (Dedekind cuts) in Mathese?

3 votes
Accepted

A couple of questions using Ramsey Theorem

3 votes

Singing Bird Problem

3 votes

Covering spaces - why are they useful?

3 votes
Accepted

Using the Catalan numbers

3 votes
Accepted

Biased lower bounded random walk