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.

Showing 1-3 of 3 results.

A156809 Number of nonisomorphic circle graphs of order n.

Original entry on oeis.org

1, 2, 4, 11, 34, 154, 978, 9497, 127954, 2165291, 42609994, 937233306, 22576188846
Offset: 1

Views

Author

Lars Eirik Danielsen (larsed(AT)ii.uib.no), Feb 16 2009

Keywords

Crossrefs

Cf. A156808.

Extensions

a(13) from Tom Johnston, Oct 17 2020

A319489 Number of non-isomorphic connected graphs on n vertices with representation number 2.

Original entry on oeis.org

0, 0, 1, 5, 20, 109, 788, 8335, 117282, 2026330, 40302424, 892278075
Offset: 1

Views

Author

Sergey Kitaev, Sep 20 2018

Keywords

Comments

These are graphs that can be represented by words having two copies of each letter, but cannot be represented by words having one copy of each letter. In a word representing a graph G, letters x and y alternate if and only if there is an edge between x and y in G. Such graphs, along with complete graphs, are precisely the class of circle graphs.

Examples

			For n=3 there is one connected graph with vertex set, say, {1,2}, which is represented by 1212.
		

Crossrefs

Equals A156808 minus 1; graphs with representation number 3 are in A319490.

A318188 Number of nonisomorphic 2-connected circle graphs of order n.

Original entry on oeis.org

0, 1, 1, 3, 10, 54, 407, 4630, 68425, 1211637
Offset: 1

Views

Author

Fidel I. Schaposnik, Sep 01 2018

Keywords

Examples

			The 3 circle graphs with n = 4 vertices which are 2-connected are K_4, the square and the square with one diagonal.
		

Crossrefs

Showing 1-3 of 3 results.