[daveguy]

M49 (for the 49th mersenne prime) fits in 2 bytes! Or even better just 49! 6 bits! Assuming your decompression algorithm is optimized for mersenne primes. :)

[alasdair_]

It can fit in a single bit if your algorithm is optimized for "primes that are equal to M49" :)

[lakofsth]

You could optimize the single bit away by assuming that there would be a bit.

[ekimekim]

http://www.dangermouse.net/esoteric/lenpeg.html

[graylights]

Great, I've just discovered the 50th mersenne prime, M50. Decompression takes a lot of time.