Number of signed graphs with n nodes. Also number of 2-multigraphs on n nodes.

A004102

Number of signed graphs with n nodes. Also number of 2-multigraphs on n nodes.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =10a(4) =66a(5) =792a(6) =25506a(7) =2302938a(8) =591901884a(9) =420784762014

External references