>except for 1, where fsqrt(c+x+f) = d - 1
If sqrt(-1) would work out to -1 instead of NaN, you'd get d-2 as well.
I've been mostly lurking since RSA1 thread. Posted from multiple devices once or twice. So that explains some of the IDs. Can't really help working on it, as I know nothing of programming and my math is atrocious. Just here because I'm interested.