A085617 - OEIS

%I #9 Mar 02 2021 04:53:12

%S 0,0,2,17,392

%N Number of nonisomorphic 2-graphs 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 two-graphs</a>, T.H.-Report 79-WSK-05, Technological University Eindhoven, Dept. Mathematics, 1979; also pp. 71-112 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&amp;gbpv=1&amp;pg=PA70&amp;printsec=frontcover">Tables of two-graphs</a>, T.H.-Report 79-WSK-05, Technological University Eindhoven, Dept. Mathematics, 1979; also pp. 71-112 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