Number of oriented multigraphs on n labeled arcs (without loops).

A020556

Number of oriented multigraphs on n labeled arcs (without loops).

Terms

    a(0) =1a(1) =1a(2) =7a(3) =87a(4) =1657a(5) =43833a(6) =1515903a(7) =65766991a(8) =3473600465a(9) =218310229201

External references