[challenge] Hamming numbers

[bearophile]

Don:
> Well, I would hate for somebody to waste their time trying to optimise 
> that problem either for speed or memory consumption, when both are 
> limited by a fairly simple, short-term library issue.

What is the short-term Phobos issue that limits the memory usage? In the current Phobos2 I have not found any easy-to-use mean to transform that eager D version into a lazy version that uses about 1/10 of the memory it currently uses (s in the second Python version).

Bye,
bearophile