k numbers adding up to n
24036
extended stars-and-bars problem(where the upper limit of the variable is bounded)
113331
Number of ways a natural number can be written as sum of smaller natural number
151179
Finding the value of $\sum k/3^k$
71616
Random numbers that sum up to specific value
57986
Sum of products of combinatorials
150647
How many $6$-lentgh increasing sequence are there from $1$ to $49$?
96173
Triangular Numbers Modulo $k$ - Hit All Values?
21000
Calculating $\sum_{k=1}^nk(k!)$ combinatorially
69943
why is ${n+1\choose k} = {n\choose k} + {n\choose k-1}$?
65757
Prove that $n! + k$ is a composite number
17213
what operation repeated $n$ times results in the addition operator?
35864
Playing with numbers form $1$ to $n^2$ in an $n\times n$ grid
107964
Simple combinatorics problem.
103840
Calculate $\sum_{k=1}^n k2^{n-k}$
131708
Sum of powers of natural numbers
140877
Evaluate the sum $\sum_{k=1}^n {n \choose k-1} {n \choose k}$
49912
Generating ordered combination of numbers