login
A006627
Number of nonisomorphic 2-graphs with n nodes with first and second cohomology invariants both 0.
(Formerly M0842)
2
1, 1, 2, 3, 7, 14, 54, 224, 2038, 32728
OFFSET
1,3
REFERENCES
Buekenhout, ed., Handbook of Incidence Geometry, 1995, p. 884.
J. J. Seidel and D. E. Taylor, Two-graphs: a second survey, pp. 689-711 of L. Lovasz and V. Sos, eds., Algebraic Methods in Graph Theory (Colloq. Janos Bolyai 25), North-Holland, 1981.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
F. C. Bussemaker, R. A. Mathon and J. J. Seidel, Tables of two-graphs, 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.
F. C. Bussemaker, R. A. Mathon and J. J. Seidel, Tables of two-graphs, 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.
CROSSREFS
Sequence in context: A238728 A271718 A222626 * A375828 A077161 A068080
KEYWORD
nonn,nice
STATUS
approved