Newbetuts

Find a recurrence relation for the number of $n$-digit binary sequences with no pair of consecutive $1$s

Counting two ways, $\sum \binom{n}{k} \binom{m}{n-k} = \binom{n+m}{n}$ [duplicate]

Find the number of ways to express 1050 as sum of consecutive integers

Number of ways two knights can be placed such that they don't attack.

1985 Putnam A1 Solution

Find the number of ways so that each boy is adjacent to at most one girl.

confusion about permutation

In how many ways can $2n$ players be paired?

In how many ways can $5$ balls of different colours be placed in $3$ boxes of different sizes if no box remains empty?

Rolling dice such that they add up to 13 — is there a more elegant way to solve this type of problem?

Explanation of the Fibonacci sequence appearing in the result of 1 divided by 89?

Number of ways to distribute objects, some identical and others not, into identical groups

proving $\binom{n-1}{k} - \binom{n-1}{k-2} = \binom{n}{k} - \binom{n}{k-1} $

Show that if four distinct integers are chosen between $1$ and $60$ inclusive, some two of them must differ by at most $19$

Given an integer base 10, is there a known way of calculating how many 1s and 0s it has in binary without counting?

How did the Symmetric group and Alternating group come to be named as such?

New posts in combinatorics

If each boy knows r girls and each girl knows r boys ,then number of boys=girls

British Olympiad; Combinatorics Recursion

Hint for problem on $4 \times 7$-chessboard problem related to pigeonhole principle

Chromatic Polynomial

Find a recurrence relation for the number of $n$-digit binary sequences with no pair of consecutive $1$s

Counting two ways, $\sum \binom{n}{k} \binom{m}{n-k} = \binom{n+m}{n}$ [duplicate]

Find the number of ways to express 1050 as sum of consecutive integers

Number of ways two knights can be placed such that they don't attack.

1985 Putnam A1 Solution

Find the number of ways so that each boy is adjacent to at most one girl.

confusion about permutation

In how many ways can $2n$ players be paired?

In how many ways can $5$ balls of different colours be placed in $3$ boxes of different sizes if no box remains empty?

Rolling dice such that they add up to 13 — is there a more elegant way to solve this type of problem?

Explanation of the Fibonacci sequence appearing in the result of 1 divided by 89?

Number of ways to distribute objects, some identical and others not, into identical groups

proving $\binom{n-1}{k} - \binom{n-1}{k-2} = \binom{n}{k} - \binom{n}{k-1} $

Show that if four distinct integers are chosen between $1$ and $60$ inclusive, some two of them must differ by at most $19$

Given an integer base 10, is there a known way of calculating how many 1s and 0s it has in binary without counting?

How did the Symmetric group and Alternating group come to be named as such?