/prog/ Challenge

Hey, I've stolen this challenge from some website, it's pretty easy but I know most of you will fuck it up.

A sequence is defined by:

n -> n/2 (n is even)
n -> 3n + 1 (n is odd)

Find the longest sequence, with a starting number under one million.

Bonus points when you find the solution for ten million.

1. you don't have to test a number if it's a member of a sequence you've already tested.

2. when a sequence reaches a power of two, the number of bits in the binary representation of that number plus the sequence 1, 4, 2, 1 is the number of terms left in the sequence.

3. A number which is two raised to an odd power can only appear at the start of a sequence, hence odd powers of two don't need to be tested since we can just set the initial known maximum sequence length to 24.

I think we'll all agree that these are all pretty trivial points, the thing that bothers me is that noone even tried to implement them (except 1).