Oh, I thought he wanted to express the result in terms of genfac
automatically. It should be doable, I think.
Martin
On 13 Aug 2003, Wolfgang Jenkner wrote:
> But Maxima's result is correct. I assume that you actually want to
> calculate
>
> (C1) nusum(k!/(k-m)!,k,m,n);
> (n + 1)!
> (D1) ----------------
> (m + 1) (n - m)!
>
> for n>=m>=0. This result is (n+1 to the m+1 falling)/(m+1), which is
> easily proven to be correct by induction wrt. n for each fixed m (you
> might prefer to introduce first a new summation index l=k-m instead).
> Note that the result you got is also correct since 1/(- m)! =
> (1/gamma)(1-m) = 0 for an integer m>=1. Your original sum also
> contains such terms in general.
>
> Wolfgang
>
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