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Answer

One can show analytically, by summing the series with k-th term k*(1-p)^(k-1)p, that the expected value of a geometric(p) random variable (the S definition of the distribution!) is equal to ((1/p) - 1) or (1-p)/p. Thus, for p=1/N, the expected value is N-1.

Albyn Jones
Tue Sep 12 11:16:10 PDT 1995