For positive integers a, b, define sequence f as follows f(1) = a f(2) = b f(n+1) = PROD(1<=k<=n; f(k)) mod SUM(1<=k<=n; f(k)). Must f(n) = 0 for some n? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://list.seqfan.eu/pipermail/seqfan/attachments/20070101/6b13123a/attachment.htm>