New posts in combinatorics

Coloring of positive integers

combinatorics elementary-set-theory coloring ramsey-theory

Chess board problem

Prove that $\sum_{q=0}^{d-r}\sum_{s=r+q}^{d}{{\binom {r-1+q}{r-1}}(r-1)!s}=\sum_{s=r}^{d}{\binom{s}{r}(r-1)!s}$ by sum manipulation [closed]

combinatorics summation binomial-coefficients factorial

Some questions concerning the symmetric group $S_n$

combinatorics group-theory symmetric-groups

How many unique numbers can be obtained from multiplying two natural numbers less than $N$?

combinatorics elementary-number-theory prime-numbers

Maximum integer not in $\{ ax+by : \gcd(a,b) = 1 \land a,b \ge 0 \}$

combinatorics number-theory analytic-number-theory combinatorial-number-theory

Minimum Size of Word Search Containing All Strings of Length $l$

combinatorics geometry graph-theory algorithms probabilistic-method

Bijection between perfect matchings permutations with even cycles

combinatorics combinatorial-proofs combinatorial-species

the sum of two arbitrary different numbers in the sequence is always coprime with the sum of three arbitrary different numbers

calculus combinatorics number-theory elementary-number-theory

When are eight integers entirely determined by their pairwise sums?

combinatorics elementary-number-theory contest-math problem-solving

Finding Expressively Adequate truth Functions

combinatorics logic binary

Average Number of Blocks in a Partition Containing a Large Block

combinatorics set-partition

How many ways can 10 teachers be divided among 5 schools?

Formula for evaluation of character on a transposition

combinatorics reference-request representation-theory integer-partitions characters

How many solutions does the equation $x_1 + x_2 + x_3 = 11$ have, where $x_1, x_2, x_3$ are nonnegative integers?

combinatorics integer-partitions

How find this minimum of the value $f(1)+f(2)+\cdots+f(100)$

combinatorics analysis elementary-set-theory inequality

Shooting game - a probability question

probability combinatorics

On the four and five color theorems

combinatorics graph-theory coloring

Does the following object have such property?

combinatorics group-theory permutations order-theory group-actions

Counting set partitions of $\{1,2,...,n\}$ into exactly $k$ non-empty subsets with max size $m$

combinatorics permutations stirling-numbers