New posts in combinatorics

How much space do I need to sort my socks?

probability combinatorics

Students who see ears of another student

combinatorics extremal-combinatorics

combinatorics - take all the balls out of a basket so that number of the balls from each color be always unequal.

combinatorics binomial-coefficients

Finding the sum $\sum_{k=1}^rk^2\binom {n-k}{r-k}$

calculus combinatorics binomial-coefficients

How many different figures can be formed with a regular polygon of $n$ vertices and a number $d$ of diagonals of this polygon?

abstract-algebra combinatorics geometry graph-theory combinations

Pouring water from bottles

combinatorics optimization algorithms

Staver's identity relating $\sum_{k=1}^{n}\binom{2k}{k}\frac{1}{k}$ and $\sum_{k=1}^{n}\left(k\binom{n}{k}\right)^{-2}$

combinatorics summation binomial-coefficients special-functions

On a combinatorial identity involving elementary symmetric polynomials

combinatorics combinatorial-proofs

Two Steps away from the Hamilton Cycle

combinatorics graph-theory

Alternative Notation for Binomial Coefficient

combinatorics reference-request notation binomial-coefficients

Dimension of the poset $(\mathbb{R}^2,\ge)$

combinatorics set-theory order-theory

Number of elements of $3n$ binary tuples, where the ordinates add up to $2n$.

combinatorics

Is it possible to shuffle a 3x3 Rubik's cube so that there's no more than 2 pieces of the same color in every face?

combinatorics group-theory recreational-mathematics rubiks-cube

Alternative proof of an intereting identity of Catalan's Numbers and central binomial coefficients

combinatorics probability-theory number-theory catalan-numbers

Number of ways to arrange objects in a circle, some of which may be identical

combinatorics algebra-precalculus discrete-mathematics necklace-and-bracelets

How many ways to colour a $4 \times 4$ grid using four colours subject to three constraints

combinatorics puzzle coloring latin-square

Numbers satisfying $\binom{n}{k} = m!$

number-theory combinatorics

Probability $k$ bins are non-empty

probability combinatorics balls-in-bins

Why is Erdős–Szekeres theorem sharp?

combinatorics

How many permutations of a multiset have a run of length k?

combinatorics permutations recurrence-relations multisets combinatorics-on-words