7.17. 1+(1+2)+(1+2+3)+....+(1+2+3+...+n).......upto n'th term.

#include<stdio.h> 
#include<conio.h>
void main ()
{
int i,n, sum=0;

clrscr ();
printf("How many number: ");
scanf("%d", &n);
for (i=1; i<=n, i++)

{

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

{

sum=sum+j;

}

}
printf("Sum= %d", sum); 
return 0; 
}