614576domain: NAppears in sequences0-sequence of reduction of (3n-2) by x^2 -> x+1.at n=20A192311Number of unimodal maps [1..n]->[0..3].at n=25A223659a(n) = Sum_{k=0..n} (-1)^k * binomial(5*n-k+1,n-k).at n=6A387756