Unexpected result with RSolve?

*To*: mathgroup at smc.vnet.net*Subject*: [mg33629] Unexpected result with RSolve?*From*: wouter.van.den.broeck at vub.ac.be*Date*: Wed, 3 Apr 2002 18:09:07 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Hey, There's probably a sound solution, but i'm struggling to grab it: RSolve[{a[n + 1] == n a[n], a[0] == 1}, a[n], n] returns: {{a[n] -> 0}} where, i believe it 'should' return {{a[n] -> (n-1)!}} Anyone care to give me some directions as to why this 'unexpected' result? (note: I started of with the standard textbook example: RSolve[{a[n] == n a[n-1], a[0] == 1}, a[n], n] which returns {{a[n] -> n!}} so there's no need to correct me in this direction, I just explored a bit, and wonder why i'm getting that result with the variation above) TIA wouter vdb