Based on Bob's suggestion, try this:

Put the number you want Gamma of in A1.

Put some other number in A2. "1" seems to work fine.

Put =GAMMADIST(A2,A1,1,FALSE) in A3

Then you can get Gamma(A1) with =EXP(-A2)*A2^(A1-1)/A3

This appears to work for positive A1.


Art