public class Pernicious{ //very simple isPrime since x will be <= Long.SIZE public static boolean isPrime(int x){ if(x < 2) return false; for(int i = 2; i < x; i++){ if(x % i == 0) return false; } return true; } public static int popCount(long x){ return Long.bitCount(x); } public static void main(String[] args){ for(long i = 1, n = 0; n < 25; i++){ if(isPrime(popCount(i))){ System.out.print(i + " "); n++; } } System.out.println(); for(long i = 888888877; i <= 888888888; i++){ if(isPrime(popCount(i))) System.out.print(i + " "); } } }