2.22292081^2 is an approximation of LN(140)
The formula should be:
S(n) = 0.5^( (n-1)^2 / LN(140) )
-- Naara elein, 23:07, 4 May 2013 (UTC)
Changed the penalty formula to a base-e form, which matches in-game values to the full displayed precision of 10^-10. Note that the decay constant of 2.67 is an exact number, not a rounded decimal!
I also reset the penalty formula in terms of a zero-based index and changed/expanded the accompanying text accordingly. This eliminates a set of nested parentheses and reduces the visual complexity of the expression, which is a virtue when writing math in plain text.