C Programming Code Examples C > Pyramid Patterns Code Examples C program to Calculate (1) + (1+2) + (1+2+3) + (1+2+3+4) + ... + (1+2+3+4+...+n) series C program to Calculate (1) + (1+2) + (1+2+3) + (1+2+3+4) + ... + (1+2+3+4+...+n) series #include<iostream.h> #include<conio.h> void main() { int x,j,n,sum=0; clrscr(); n=10; for(x=1;x<=n;x++) { for(j=1;j<=x;j++) { sum+=j; } } cout<<"Sum: "<<sum; getch(); }