|a(n+p)-a(n)|=1/(n+1)^2+...+1/(n+p)^2<1/[n(n+1)]+1/[(n+1)(n+2)]+...+1/[(n+p-1)(n+p)]=1/n-1/(n+1)+1/(n+1)-1/(n+2)+...+1/(n+p-1)-1/(n+p)=1/n-1/(n+p)<1/n,取N=【1/e】+1,任意的n>N,有|a(n+p)-a(n)|
等号前面是错的,应该是 >1/(n+n)+1/(n+n)+……+1/(n+n)=n/(n+n)=1/2, 你仔细看看。。。