Question

How many surjective functions from $A=\{1, 2, 3, 4\}$ to $B=\{a, b, c\}$ when $4 \mapsto c$?

score 82 · Answer 1 · 2026-04-16 00:10:07

82

Views

How many surjective functions from $A=\{1, 2, 3, 4\}$ to $B=\{a, b, c\}$ when $4 \mapsto c$?

Published on 16 Apr 2026 - 0:10

score 69 · Answer 2 · 2026-04-13 07:23:31

69

Views

Combinatorial Meaning of the Binomial Coefficient $s\choose k$?

Published on 13 Apr 2026 - 7:23

score 93 · Answer 3 · 2026-05-10 15:03:30

93

Views

8-element permutations of a multiset {3:0,1:1,1:3,1:5,1:8,1:9} with the restriction 0 is not allowed in left or rightmost position

Published on 10 May 2026 - 15:03

score 23 · Answer 4 · 2026-04-16 15:05:03

23

Views

Calculate the amount of words from the alphabet $(A,B)$ that contains seven $A$ and four $B$.

Published on 16 Apr 2026 - 15:05

score 24 · Answer 5 · 2026-04-11 01:43:59

24

Views

Combinatory Problem, all the different ways to do this combinatory problem

Published on 11 Apr 2026 - 1:43

score 40 · Answer 6 · 2026-04-14 22:13:11

How many ways are there to paint an $n$-storey block of flats if each level must be painted black or white with the given restrictions?

score 83 · Answer 7 · 2026-04-14 10:28:51

83

Views

Number of integer solutions of $3x+y+z=23$

Published on 14 Apr 2026 - 10:28

score 158 · Answer 8 · 2026-05-10 12:54:07

158

Views

Quantity of same numbers in same positions of permutations and its resort

Published on 10 May 2026 - 12:54

score 81 · Answer 9 · 2026-05-14 12:36:16

81

Views

how can I prove that $p=7,n=2$ is the only solution (sum of divisors)?

Published on 14 May 2026 - 12:36

score 670 · Answer 10 · 2026-05-11 00:27:31

670

Views

Finding all combinations that sum up to a specific number with given constrains

Published on 11 May 2026 - 0:27

score 691 · Answer 11 · 2026-04-14 13:00:02

691

Views

Probability that 3 vertices of a 2n+1 sided polygon chosen at random form vertices of an isosceles triangle

Published on 14 Apr 2026 - 13:00

score 2.1k · Answer 12 · 2026-04-15 14:38:47

What's wrong in my solution? Ways of choosing 5 items from 3 catagory with 3, 6, 14 items, while having 1 item from each catagory.

score 52 · Answer 13 · 2026-04-15 12:07:33

52

Views

on the Frobenius number (J. L Davison)

Published on 15 Apr 2026 - 12:07

score 109 · Answer 14 · 2026-05-14 12:38:47

109

Views

if $d|n$, then $S_2(d) \leq S_2(n)$?

Published on 14 May 2026 - 12:38

score 721 · Answer 15 · 2026-04-14 22:38:43

721

Views

Can you determine a set of values from a set of sums?

Published on 14 Apr 2026 - 22:38

List Question

How many surjective functions from $A=\{1, 2, 3, 4\}$ to $B=\{a, b, c\}$ when $4 \mapsto c$?

Combinatorial Meaning of the Binomial Coefficient $s\choose k$?

8-element permutations of a multiset {3:0,1:1,1:3,1:5,1:8,1:9} with the restriction 0 is not allowed in left or rightmost position

Calculate the amount of words from the alphabet $(A,B)$ that contains seven $A$ and four $B$.

Combinatory Problem, all the different ways to do this combinatory problem

How many ways are there to paint an $n$-storey block of flats if each level must be painted black or white with the given restrictions?

Number of integer solutions of $3x+y+z=23$

Quantity of same numbers in same positions of permutations and its resort

how can I prove that $p=7,n=2$ is the only solution (sum of divisors)?

Finding all combinations that sum up to a specific number with given constrains

Probability that 3 vertices of a 2n+1 sided polygon chosen at random form vertices of an isosceles triangle

What's wrong in my solution? Ways of choosing 5 items from 3 catagory with 3, 6, 14 items, while having 1 item from each catagory.

on the Frobenius number (J. L Davison)

if $d|n$, then $S_2(d) \leq S_2(n)$?

Can you determine a set of values from a set of sums?

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