cp's OEIS Frontend

C

#include 
#include 
#include 
#define TOP (1ULL<<32)  // Memory usage: 0.5 Gb
int main() {
  unsigned long long i, j, p, t, r;
  unsigned char *c = (unsigned char *)malloc(TOP/8);
  memset(c, 0, TOP/8);
  for (printf("0, "), i=1; i < TOP; i+=2)
    if ((c[i>>4] & (1<<((i>>1)&7))) == 0) {
      for (p = i + (i==1), j = p*p; ; j*=p) {
        t = j - 1;
        r = sqrt(t*2);
        if (r*(r+1)==t*2)  printf("%llu, ", r);
        double k = ((double)j) * ((double)p);
        if (k >= ((double)(1ULL<<62)*4.0)) break;
      }
      if (i>1) for (j=i*i>>1; j>3] |= 1 << (j&7);
    }
  // SORT the output
  return 0;
}