256564

Appears in sequences

• Number of different n X n symmetric matrices with nonnegative entries summing to 4. Also number of symmetric oriented graphs with 4 arcs on n points.at n=28A139594
• a(n) = n*(3*n^4 + 15*n^3 + 25*n^2 - 15*n - 28)/60.at n=21A365373