Summation of nth-degree nos.

2009-09-26 9:04 pm
Is there a formula for summing up a sequence of numbers with a power of n, i.e.,

1^n + 2^n + ... + m^n

Just like 1 + 2 + 3 + ... + m = 0.5*m*(m+1).

回答 (1)

2009-09-26 10:39 pm
✔ 最佳答案
Denote Sk (n)=1^k + 2^k + ... + n^k. There exist a recursive formula such that you can use the previous formula of Sk-1 (n), Sk-2 (n),... S1 (n) to find out Sk (n)
k+1C1Sk (n)+ k+1C2Sk-1 (n)+...+k+1Ck+1S0 (n)=(n+1)k+1-1
where S0 (n)=n.
For example, 2C1S1 (n)+2C2S0 (n)=(n+1)2-1
S1 (n)=(n2+2n-n)/2=n(n+1)/2
There is a similar formula which is related to Bernoulli numbers. However, since to find out those Bernoulli numbers also requires using other recursive formulae. So, I omit them here.


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