That was the first thing I tried, but it blew the stack :) You can still blow the stack if you pick a number that's too high, like k[20000] or something. But

That was the first thing I tried, but it blew the stack :) You can still blow the stack if you pick a number that's too high, like k[20000] or something. But if you pick a lower number & cache that, then you can (eventually) call a higher number without blowing the stack. This recursive approach is a horribly inefficient algorithm anyway, so I don't think it's worth optimizing :)