[tromp]

Your page only mentions

> Upper bound estimate of possible legal chess position (counts en passant, castling, sides to move, allows underpromotions): 8.7E+45.

But how exactly is this number determined? Is this a sampling based estimate?

My 8726713169886222032347729969256422370854716254 is an exact upperbound on the number of so-called urpositions, and is not sampling based.

In any case it will be easier to continue this discussion at https://github.com/lechmazur/ChessCounter/issues/1