比如
yma16
2024-07-16 22:10:57
( reads)
There's a formula for the sum of n(n+1)(n+2) from 1 to k:
Σ[n(n+1)(n+2)] from n=1 to k = (k(k+1)(k+2)(k+3))/4
There's a formula for the sum of n(n+1)(n+2) from 1 to k:
Σ[n(n+1)(n+2)] from n=1 to k = (k(k+1)(k+2)(k+3))/4