#include "stdio.h"main(){int n,s;n=1;s=0;while(n<51){s=s+n*(n+1)*(n+2);n++;}printf("S=%d",s);}
int a=1;int b=2;int sum=0;for(int n=1;n<=20;n++){ sum+= a*b; a++; b++;}
