4668304

Appears in sequences

• Number of n X 3 0..3 arrays with rows, diagonals and antidiagonals unimodal and columns nondecreasing.at n=8A224168
• a(n) = (3/n^3) * Sum_{d|n} (-1)^(n+d)*moebius(n/d)*binomial(2*d,d).at n=17A254593