I guess you needed to specify exactly what you meant by "buyinscount", and for which formula you are needing this variable.

For the Points for Playing formula, or for the Score formula, the variable "numberOfPlayers" or "n" represents the number of players who have bought-in to the tournament. Since a player can only buy-in once (any further "buy-ins" would be "rebuys"), this also represents the "buyinscount", in the sense of "the number of buy-ins for the tournament". If you meant "how many times a player bought-in", this is always 1 for any tournament, so it is a useless number for Points for Playing or Score formulas.

For the Overall Score formula, the variable "numberOfTournaments" or "n" represents the number of tournaments that passed your filter (or the number of tournaments over which we are calculating stats). The "numberOfScores" or "s" represents the number of scores a player has, which also equals the number of tournaments in which the player participated. You can also get this by using the count() function: "count(scores)" will return the same number. I failed to document "numberOfScores" and "s" in the user manual, I think.