cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Previous Showing 31-32 of 32 results.

A101390 Number of n-vertex unlabeled mating graphs (cf. A006024) without endpoints.

Original entry on oeis.org

1, 0, 1, 2, 7, 41, 347, 5447, 158097, 8456025
Offset: 1

Views

Author

Goran Kilibarda, Zoran Maksimovic, Vladeta Jovovic, Jan 14 2005

Keywords

Crossrefs

Cf. A006024, A004108, A004110, A059167.

A133279 Number of unlabeled mating graphs with n nodes and a degenerate adjacency matrix.

Original entry on oeis.org

1, 0, 1, 1, 7, 21, 234, 2252, 64420, 2148355, 183956671
Offset: 1

Views

Author

Tanya Khovanova, Aug 27 2008

Keywords

Comments

Mating graphs are graphs where no two nodes have the same set of neighbors.
Graphs with an invertible adjacency matrix are mating graphs.

Crossrefs

Cf. A004110, A109717.

Programs

  • Mathematica
    k = {}; For[i = 1, i < 8, i++, lg = ListGraphs[i] ; len = Length[lg]; k = Append[k, Length[Select[Range[len], Det[ToAdjacencyMatrix[lg[[ # ]]]] == 0 && Length[Union[ToAdjacencyMatrix[lg[[ # ]]]]] == i &]]]]; k

Formula

a(n) = A004110(n) - A109717(n).

Extensions

a(8)-a(11) by Shreeyash Gotmare, Aug 28 2017
Previous Showing 31-32 of 32 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.