/*
  Summatories
*/
int main(){
  sum(i) from 1 to n = n(n+1)/2
  sum(i^2) from 1 to n = n(n+1)(2n+1)/6
  sum(i^3)  from 1 to n = (n^2(n+1)^2)/4
}

Add equations for some summatories.
Add equations for some summatories.
