> That said, I do think it's neat that the fastest brute-force variant is a rough factor-2 from your naïve memoized version. My naive memoized version in a GCd

> That said, I do think it's neat that the fastest brute-force variant is a rough factor-2 from your naïve memoized version. My naive memoized version in a GCd language that is consistently 4-5x slower than my own (pretty bad) C versions of the same project Euler problems without any of the tricks the fastest C++ version is doing. Still pretty impressive considering most solutions in the project euler forums take more than 1s.