Summation of $\sum_{i=1}^n i2^i.$
562
Formula for calculating $\sum_{n=0}^{m}nr^n$
97266
Summation by parts (finite calculus) of $\sum\limits_{i=0}^{n}i\cdot a^i$
17453
What is sum of $\sum_{x=1}^n x \log (x)$
115433
Find the summation of given expression: $\sum_{k=1}^n k^3\binom nk$
23557
Algebraic Proof that $\sum\limits_{i=0}^n \binom{n}{i}=2^n$
143365
Is $\sum_{i=1}^{n-1}i=\binom{n}{2}$?
48200
Simplify $\sum_{i=0}^n (i+1)\binom ni$
143207
What is $\sum\limits_{i=1}^n \sqrt i\ $?
33104
Combinatorial Proof with Summation Identity
108318
counting proof for $\sum_{k=0}^{n-1} 2^{k} = 2^n - 1$
155479
Summation of inner products
52113
Proof by Induction $\sum_{i=0}^{k-1} 2^i = 2^k-1$
2885
Prove that $\sum\limits_{i=1}^n 2i\binom{2n}{n-i}= n\binom{2n}{n}$
99001
General identity for a double summation theorem
83229
Nested summations and their relation to binomial coefficients
128913
A proof of $\sum_{i=1}^{n}(-1)^{i-1}\binom{n}{i}\frac{1}{i}=\frac{1}{1}+\frac{1}{2}+....+\frac{1}{n}$
127150
Finding general formula of $\sum_{i=0}^n i^2 \binom{n}{i}$