Number of connected labeled 2-regular relations of order n.

A123544

Number of connected labeled 2-regular relations of order n.

Terms

    a(0) =0a(1) =0a(2) =1a(3) =6a(4) =87a(5) =1980a(6) =66270a(7) =3050460a(8) =184716630a(9) =14231775600

External references