(1.2.3)+(2.3.4)+(3.4.5)+........n

(1.2.3)+(2.3.4)+(3.4.5)+........n

 

//1.2.3+2.3.4+3.4.5+........n

#include<stdio.h>

int main()

{

    int n,i,sum=0;

    printf("enter number= ");

    scanf("%d",&n);

    for(i=1;i<=n;i=i++)

         sum=sum+(i+1)*i*(i+2);

    {

    printf("\n%d\n",sum);

    }

}