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A085617 Number of nonisomorphic 2-graphs with 2n nodes with first cohomology invariant nonzero, second cohomology invariant 0. 1
0, 0, 2, 17, 392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..5.

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

Cf. A006627, A002854.

Sequence in context: A319591 A198405 A202972 * A152557 A015202 A308864

Adjacent sequences:  A085614 A085615 A085616 * A085618 A085619 A085620

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jul 11 2003

STATUS

approved

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Last modified May 12 07:28 EDT 2021. Contains 343821 sequences. (Running on oeis4.)