Compute the upper bound correctly.
Compute the upper bound correctly.

The largest thing *known* to be prime is the last entry of the bitv,
which corresponds to (len - 1)*2+1, not len*2+1.

Antiarchitect/primal,huonw/primal,wackywendell/primal,Antiarchitect/primal,wackywendell/primal,huonw/slow_primes,cuviper/primal,huonw/primal,cuviper/primal