160890

Appears in sequences

• Number of connected labeled 2-regular pseudodigraphs (multiple arcs and loops allowed) of order n.at n=6A123543
• Sum of the principal diagonals of a 2n X 2n square spiral.at n=31A137931
• Triangle T(n,k) read by rows: number of labeled 2-regular digraphs (multiple arcs and loops allowed) on n nodes with k components.at n=22A307804