比如

来源: yma16 于 2024-07-16 22:10:57 [档案] [博客] [旧帖] [给我悄悄话] 本文已被阅读：次 (4398 bytes)

回答: 这类的和有公式。由 yma16 于 2024-07-16 22:09:11

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