Expected Probability Adjustment Equations

Hello;

I'm looking for a set of equations expressing the Expected probability in terms of the (associated) Exceedance probability and the sample size. A selected set of these equations are actually depicted in some docs I've got (the Bulletin #17B -March 1982, Chow,et al, Applied Hydrology-1988, & HEC-REGFRQ users manual-1972/82) but, these do not cover a number of cases
one frequently encounters in practice (notably, 20%, 4%, 2%, 0.5%, 0.2%, and 0.05% chances).

I'd therefore, highly appreciate any guidance & help from those of you who might have seen a rather comprehensive set of these equations somewhere and could refer me to or, have already derived the equations for some or all of the probability levels said - thus saving me the time needed to go up & down the tables.

Thank you.

Mostafa Bozorg-Zadeh