Find the sum $ 1 \cdot 1! + 2 \cdot 2! + 3 \cdot 3! + ... + n \cdot n! $
91933
Evaluate $\sum_{k=1}^nk\cdot k!$
106888
Factorial identity $n!=1+(1-1/1!)n+(1-1/1!+1/2!)n(n-1)+\cdots$
148949
Find the value of $\sum_{k=1}^{n} k \binom {n} {k}$
124135
A general formula for $\sum (k-1)(k-2)(k-3)$?
27001
How to calculate the following sum:
100896
What is the sum of this? $ 1 + \frac12 + \frac13 + \frac14 + \frac16 + \frac18 + \frac19 + \frac1{12} +\cdots$
91410
Finding the sum of this series: $1+\frac 12 + \frac 13 + \cdots + \frac 1{50}$
36436
Proving $\sum_{k=1}^n k k!=(n+1)!-1$
65672
Proof of the summation $n!=\sum_{k=0}^n \binom{n}{k}(n-k+1)^n(-1)^k$?
103343
Finding $\frac{3}{1!+2!+3!}+\frac{4}{2!+3!+4!} +\frac{5}{3!+4!+5!}+\cdots+\frac{2008}{2006!+2007!+2008!}$
155611
Sum of series $\frac{1}{2 \cdot 3 \cdot 4} + \frac{1}{4 \cdot 5 \cdot 6} + \frac{1}{6 \cdot 7 \cdot 8} + \cdots $
26087
Find all natural numbers $n > 1$ and $m > 1$ such that $1!3!5!\cdots(2n - 1)! = m!$
92704
Prove that $\sum_{k=1}^{n}k\binom{n}{k}=n\cdot2^{n-1}$
149010
Finding Combinations to the provided Sum value
103840
Calculate $\sum_{k=1}^n k2^{n-k}$
63553
Show that $\frac{1}{(n+1)!}(1+\frac{1}{(n+1)}+\frac{1}{(n+1)^2}+\frac{1}{(n+1)^3}+\cdots)=\frac{1}{n!n}$
114889
Solve summation $\sum_{i=1}^n \lfloor e\cdot i \rfloor $