http://www.portugal-a-programar.pt/topic/66422-repeticao-122/

gistfile1.c

#include <stdio.h>

static int inicial = 1;
static int final = 5;

int
main (int argc, char **args)
{
  int cont = 0;
  int pos = inicial;

  while (pos <= final && cont <= final)
    {
      printf ("%d ", pos);
      if (cont == pos - 1)
        {
          pos++;
          cont = 0;
        }
      else
        cont++;
    }
}