This Should Ring a Bell

#include <stdio.h>
int main()
{
  const int limit = 1000;
  int x;
  float t;
  /* divergent */
  t = 0.0;
  for(x=1; x<=limit; x++ ) t += 1.0 / (float)x;
    printf("Divergent: %.4f\n", t);
  /* convergent */
  t = 0.0;
  for(x=1; x<=limit; x*=2 ) t += 1.0 / (float)x;
    printf("Convergent: %.4f\n", t);
    
  return(0);
}