How to get inverse of formula for sum of integers from 1 to n?
75279
Reversing the $T(n) = \frac{n(n+1)}{2}$ formula
70248
Closed-form expression for $\sum_{k=0}^n\binom{n}kk^p$ for integers $n,\,p$
562
Formula for calculating $\sum_{n=0}^{m}nr^n$
143132
How to reverse the $n$ choose $k$ formula?
127150
Finding general formula of $\sum_{i=0}^n i^2 \binom{n}{i}$
110262
Finding a closed formula for $1\cdot2\cdot3\cdots k +\dots + n(n+1)(n+2)\cdots(k+n-1)$
14540
Any shortcut to calculate factorial of a number (Without calculator or n to 1)?
146305
Simplify sum of factorials with mathematical induction
68725
Find expression for : $ S_n =\sum_{i=1}^{n} \frac{i}{i^4+i^2+1} $
145768
The inverse of a matrix in which the sum of each row is $1$
63474
Showing $\sum_{i = 1}^n\frac1{i(i+1)} = 1-\frac1{n+1}$ without induction?
30518
Formula for $\sum_{k=1}^n \frac{1}{k(k+1)(k+2)}$?
115236
Calculate the sum of inverse values of ${n\choose 0}, {n\choose 1}, ... {n\choose n}$
35034
Multiplicative inverses for $Z_n$
39659
Is there a closed formula for this summation?
113950
Formula for reversing digits of positive integer $n$
38741
Finding a general formula for summation