%I
%S 0,0,2,17,392
%N Number of nonisomorphic 2graphs with 2n nodes with first cohomology invariant nonzero, second cohomology invariant 0.
%H F. C. Bussemaker, R. A. Mathon and J. J. Seidel, <a href="https://link.springer.com/content/pdf/10.1007/BFb0092256.pdf">Tables of twographs</a>, T.H.Report 79WSK05, Technological University Eindhoven, Dept. Mathematics, 1979; also pp. 71112 of "Combinatorics and Graph Theory (Calcutta, 1980)", Lect. Notes Math. 885, 1981.
%H F. C. Bussemaker, R. A. Mathon and J. J. Seidel, <a href="https://www.google.com/books/edition/Combinatorics_and_Graph_Theory/KD17CwAAQBAJ?hl=en&gbpv=1&pg=PA70&printsec=frontcover">Tables of twographs</a>, T.H.Report 79WSK05, Technological University Eindhoven, Dept. Mathematics, 1979; also pp. 71112 of "Combinatorics and Graph Theory (Calcutta, 1980)", Lect. Notes Math. 885, 1981.
%Y Cf. A006627, A002854.
%K nonn
%O 1,3
%A _N. J. A. Sloane_, Jul 11 2003
