How do I do this counting problem?
52056
Chromatic Triangles on a $K_{17}$ graph
108941
Combinatorics Question Asking How Many Integer Solutions Given Different Restrictions
68882
Path to Combinatorics Problem [$1.11$]
129848
Counting the number of occurences of characters in a string
26569
Counting binary operations on a set with $n$ elements
158284
How to Solve this Arithmetic Progression Question?
106673
Race Problem counting
53631
Probability question (Birthday problem)
158050
Counting words in a string?
70515
Recursion and Counting
144025
Number of Solutions in this Number Puzzle
139442
How can i count number of digits in tetrated numbers?
66620
How do I get the number of elements in a list?
94784
$\sum_{k=-m}^{n} \binom{m+k}{r} \binom{n-k}{s} =\binom{m+n+1}{r+s+1}$ using Counting argument
6679
Counting number of subsets which contain a specific element
90068
Calculating the number of times a digit is written when given two numbers
104268
Confusion on how to solve this question about sequences.