Newbetuts

Is it possible to cover a $70\times70$ torus (or klein bottle/projective plane) with $24$ squares with side length $1,2,3\ldots,24$?

Given $n$ identical resistors $R$, find combinations of series, parallel, and series-parallel arrangements

Proving an identity for complete homogenous symmetric polynomials

Let $x$ be an irrational number. Prove that there exist infinitely many rational numbers $\dfrac pq$ that satisfy the following

How to win Matt Parker's jackpot - finding the median of the following distribution

Probability that all bins contain strictly more than one ball?

Direct proof of Gelfand-Zetlin identity

A proof of the identity $ \sum_{k = 0}^{n} \frac{(-1)^{k} \binom{n}{k}}{x + k} = \frac{n!}{(x + 0) (x + 1) \cdots (x + n)} $.

Minimum steps adding edges to form a complete graph

Arrangements question.

Euler function and sums

Domino Tiling 8 x 8 grid proof

Coefficient of $x^{n-2}$ in $(x-1)(x-2)(x-3)\dotsm(x-n)$

Reverse Littlewood-Offord problem: lower bound for the number of choices of signs such that $|\pm a_1\dots\pm a_n| \leq \max|a_i|.$

Old USAMO combinatorics problem about distribution of members into committees containing a fixed number of members.

What is the best way to partition the $4$-subsets of $\{1,2,3,\dots,n\}$?

How would you go about learning the combination of coins the man has?

New posts in combinatorics

Is it possible to cover a $70\times70$ torus (or klein bottle/projective plane) with $24$ squares with side length $1,2,3\ldots,24$?

Product of binomial coefficient as a basis

How many arrangements of a (generalized) deck of (generalised) cards have pairs in them?

Dimension of the space of algebraic Riemann curvature tensors

Given $n$ identical resistors $R$, find combinations of series, parallel, and series-parallel arrangements

Proving an identity for complete homogenous symmetric polynomials

Let $x$ be an irrational number. Prove that there exist infinitely many rational numbers $\dfrac pq$ that satisfy the following

How to win Matt Parker's jackpot - finding the median of the following distribution

Probability that all bins contain strictly more than one ball?

Direct proof of Gelfand-Zetlin identity

A proof of the identity $ \sum_{k = 0}^{n} \frac{(-1)^{k} \binom{n}{k}}{x + k} = \frac{n!}{(x + 0) (x + 1) \cdots (x + n)} $.

Minimum steps adding edges to form a complete graph

Arrangements question.

Euler function and sums

Domino Tiling 8 x 8 grid proof

Coefficient of $x^{n-2}$ in $(x-1)(x-2)(x-3)\dotsm(x-n)$

Reverse Littlewood-Offord problem: lower bound for the number of choices of signs such that $|\pm a_1\dots\pm a_n| \leq \max|a_i|.$

Old USAMO combinatorics problem about distribution of members into committees containing a fixed number of members.

What is the best way to partition the $4$-subsets of $\{1,2,3,\dots,n\}$?

How would you go about learning the combination of coins the man has?