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 1-5 of 5 results.

A126750 Number of 2-connected (or biconnected) graphs on n nodes with chromatic number 2.

Original entry on oeis.org

0, 0, 0, 1, 1, 5, 8, 42, 146, 956, 6643, 65921, 818448, 13442572, 287665498, 8099980771, 300760170216, 14791653463768, 967055338887805, 84368806391412395, 9855854129239183783, 1546801291978378704267
Offset: 1

Views

Author

N. J. A. Sloane, Feb 18 2007, Oct 01 2008

Keywords

Comments

Equally, number of 2-connected (or biconnected) bipartite graphs on n nodes.
Also number of biconnected triangle-free graphs on n nodes with chromatic number 2, since chromatic number 2 implies triangle-free. - Gordon Royle, Apr 11 2007
See the Gainer-Dewar/Gessel reference for formulas and Sage code. - Ralf Stephan, May 18 2013

Links

Crossrefs

A diagonal of triangle in A126749.

A126754 Number of biconnected graphs on n nodes with chromatic number 6.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 4, 59, 1631, 101409, 13626123
Offset: 1

Views

Author

N. J. A. Sloane, Feb 18 2007

Keywords

Comments

It is possible that the definition should say "connected" rather than "biconnected". Should be rechecked! - Max Alekseyev and Brendan McKay, Jun 17 2008

Links

Crossrefs

A diagonal of triangle in A126749.

Extensions

a(11) from Michael Sollami, Feb 18 2012

A126751 Number of biconnected graphs on n nodes with chromatic number 3.

Original entry on oeis.org

0, 0, 1, 1, 6, 30, 232, 2762, 50814, 1420183, 58836784
Offset: 1

Views

Author

N. J. A. Sloane, Feb 18 2007

Keywords

Links

Crossrefs

A diagonal of triangle in A126749.
The sequence for "connected" is A126737.

Extensions

a(11) from Michael Sollami, Feb 18 2012

A126752 Number of biconnected graphs on n nodes with chromatic number 4.

Original entry on oeis.org

0, 0, 0, 1, 2, 17, 189, 3627, 118114, 6530233, 596566067
Offset: 1

Views

Author

N. J. A. Sloane, Feb 18 2007

Keywords

Comments

It is possible that the definition should say "connected" rather than "biconnected". Should be rechecked! - Max Alekseyev and Brendan McKay, Jun 17 2008

Links

Crossrefs

A diagonal of triangle in A126749.

Extensions

a(11) from Michael Sollami, Feb 18 2012

A126753 Number of biconnected graphs on n nodes with chromatic number 5.

Original entry on oeis.org

0, 0, 0, 0, 1, 3, 34, 627, 23262, 1686975, 231563309
Offset: 1

Views

Author

N. J. A. Sloane, Feb 18 2007

Keywords

Comments

It is possible that the definition should say "connected" rather than "biconnected". Should be rechecked! - Max Alekseyev and Brendan McKay, Jun 17 2008

Links

Crossrefs

A diagonal of triangle in A126749.

Extensions

a(11) from Michael Sollami, Feb 18 2012
Showing 1-5 of 5 results.

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

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