1,最基本的 :s=1+(1+2)+(1+2+3)+···+(1+2+3+···+n)
#include "stdafx.h" int f(int a) { if (a > 1) return a + f(a - 1); else return a; } int main(int argc, char* argv[]) { int n =10; int s =0; printf("n =10; s = %d/n",f(n)); return 0; }