Sure you can. Here's a super grotty (and expensive) c# version. static IEnumerable<int> infinite() { int x = 2; while

Sure you can. Here's a super grotty (and expensive) c# version. static IEnumerable<int> infinite() { int x = 2; while (true) { yield return x++; } } static IEnumerable<int> primes(IEnumerable<int> l) { int head = l.First(); yield return head; foreach (var x in primes(l.Skip(1).Where(x => x % head != 0))) yield return x; } static void Main(string[] args) { System.Console.WriteLine(string.Join(",", primes(infinite()).Take(20).Select(x => x.ToString()))); }