On Thu, Jan 13, 2011 at 1:23 PM, Ron Hardin <rhhardin at att.net> wrote: > what's 2,8,16,30,50,77,112 ? If the 8 were 7, it'd look a lot like A005581, (n-1)*n*(n+4)/6: 0, 0, 2, 7, 16, 30, 50, 77, 112. so possibly perturbing that in some way might help. Doug -- Department of Earth Sciences University of Hong Kong