Day 69: Errata in 3-5 positions.

Ok, This is bad. Positions for the "lower part of the board" in 19x19 (103,65,117,74 are good) are:

303: (n+1)*15+3
345: (n+1)*17+5
317: (n+1)*16-3
335: (n+1)*17-5

Next, CODE!