比如

來源: yma16 於 2024-07-16 22:10:57 [] [博客] [舊帖] [給我悄悄話] 閱讀數 : (4398 bytes)
回答: 這類的和有公式。 由 yma16 於 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

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