'Mixing number' of permutations

[Brendan McKay]

* Edwin Clark <eclark at math.usf.edu> [060818 00:40]:
> For what it may be worth Maple simplifies  sum(1/binomial(n,k),k=1..n-1) 
> to: 
> 
> -1/2*1/n*(n^2*LerchPhi(2,1,n)+2^(-n)*Pi*n^2*I+n+n*LerchPhi(2,1,n)+2^(-n)*Pi*n*I-1)

Yes, that's why I said I didn't know of a closed form ;-).
LerchPhi(2,1,n) is some complex-valued function of n, yuk.

Brendan.