New test to see exactly what the error consists of. In this test I start with odd numbers, just to get this checked at the same time. Since no one moves, the number of players must be halved + 1 from round to round.

41 players 4 rounds should give:

1: 20 boards and 1 bye 2: 10 boards and 1 bye 3: 5 boards and 1 bye 4: 3 boards and 0 byes