Number of nonisomorphic 2-graphs with n nodes with first and second cohomology invariants both 0.

A006627

Number of nonisomorphic 2-graphs with n nodes with first and second cohomology invariants both 0.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =3a(4) =7a(5) =14a(6) =54a(7) =224a(8) =2038a(9) =32728

External references