[seqfan] Re: Number of solutions of a*b + c*d + ... + y*z = 0 (mod n)

[Max Alekseyev]

On Sun, Sep 5, 2010 at 9:10 PM, Ron Hardin <rhhardin at att.net> wrote:
> How many distinct no-zero solutions are there of a sum of k products of pairs
> of numbers in 1..n-1 such that the sum is zero (mod n)?

Btw, why do you exclude 0?
Would it be more natural to allow full range of residues modulo n to
participate in the solutions?

Regards,
Max