User blog comment:LittlePeng9/Random Turing machines/@comment-1605058-20130411200122/@comment-5529393-20130412130438

Ah, I see. For some reason I interpreted the s as plural. But the bound seems to give 7*2*2*45 = 1260 rather than 540 - unless that 2^(n+1) should be a 2^n instead.

Anyway, I would love to see the construction.