The P-1 choice lets you factor
Mersenne numbers using the P-1 method of factoring. There is presently no web site which tells you how much P-1
factoring has already been done on exponents.
You can also edit the worktodo.ini file directly. For example:
Pminus1=751001,1000000,0,0,0
The first value is the exponent. The second value is bound #1. The third value is bound #2. The fourth value is 0 for 2^N-1 factoring, 1
for 2^N+1 factoring. The fifth value is
no longer used.