关于1~k+2~k+…+n^k求和的三种方法

The Three Methods to 1~k+2~k+...+n^k

就差分方法、伯努利公式以及组合公式三种方法对 ∑ni=1ik求和 .

Three methods to 1 k+2 k+...+n k are introduced. i.e. differencial method, Bernoulli formula, combined equation.