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 1-2 of 2 results.

A343869 Number of unlabeled nonseparable (or 2-connected) planar graphs with n edges.

Original entry on oeis.org

1, 0, 1, 1, 2, 4, 7, 16, 41, 108, 320, 1042, 3575, 13064, 49938, 197729, 805991, 3363084, 14302891, 61813285, 270805177, 1200460492, 5376709415, 24302430375, 110745093999, 508380790741
Offset: 1

Views

Author

Andrew Howroyd, May 04 2021

Keywords

Comments

Terms may be computed using the tools geng and planarg in nauty.

Links

Crossrefs

Row sums of A343870.
Column sums of A049336(n > 1).
Cf. A002840 (3-connected), A010355, A021103, A046091, A289471, A291841.

Programs

  • nauty
    # count graphs for the sequence by number of vertices v, sum over v afterwards
geng -C $v $n:$n | planarg -q | countg -q # Georg Grasegger, Jun 05 2023

Extensions

a(21)-a(26) added by Georg Grasegger, Jun 05 2023

A289470 Number of strictly 2-connected graphs with n edges.

Original entry on oeis.org

1, 0, 1, 1, 2, 3, 7, 15, 39, 107, 324, 1072, 3778, 14228, 56568, 235449, 1021381, 4596328, 21383982, 102594132, 506544749, 2569520447, 13372902590, 71322154244, 389402949706
Offset: 1

Views

Author

Ed Pegg Jr, Jul 06 2017

Keywords

Crossrefs

Cf. A002218, A002840, A010355, A289471, A338511.

Formula

a(n) = A010355(n) - A338511(n). - Andrew Howroyd, May 03 2021

Extensions

a(12)-a(13) corrected and a(14)-a(25) from Andrew Howroyd, May 03 2021
Showing 1-2 of 2 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.