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.

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A338583 Number of unlabeled 3-connected nonplanar graphs with n edges.

Original entry on oeis.org

1, 2, 3, 10, 29, 94, 343, 1291, 5206, 22061, 96908, 439837, 2053916, 9841412, 48319944, 242857491, 1248629027, 6563581656, 35258560001, 193463945790
Offset: 9

Views

Author

Hugo Pfoertner, Nov 21 2020

Keywords

Links

Crossrefs

Cf. A002840, A006290, A337517, A338197, A338511, A338573, A338584, A338593, A338594, A338604.

Formula

a(n) = A338511(n) - A002840(n).
a(n) <= A338593(n). The difference A338584(n) = A338593(n)-a(n) are the counts of nonplanar connected graphs with minimum degree 3 at each node that are not 3-connected.

A338414 Number of labeled 3-connected graphs with n edges.

Original entry on oeis.org

1, 0, 15, 80, 493, 5730, 45790, 501690, 5747805, 66738169, 884847355, 12032825028, 174686734180, 2698980641742, 43470161714616, 739558796434277, 13161203468888236, 244555222834161480
Offset: 6

Views

Author

Andrew Howroyd, Nov 07 2020

Keywords

Comments

The initial terms of this sequence were computed from A123542.
The smallest 3-connected graph is the complete graph on 4 vertices which has 6 edges.

Crossrefs

Cf. A005644, A007100, A123542, A322139, A338511.

A339068 Number of unlabeled series-reduced 2-connected graphs with n edges.

Original entry on oeis.org

1, 0, 1, 3, 5, 9, 26, 65, 193, 632, 2173, 8049, 31690, 130773, 563849, 2525348, 11702264, 55948154, 275331956, 1392136462, 7221272289, 38380011748, 208778309856
Offset: 6

Views

Author

Andrew Howroyd, Nov 24 2020

Keywords

Crossrefs

Column sums of A339069.
Cf. A006289, A010355, A338511.

A340920 a(n) is the number of distinct resistances that can be produced from a planar circuit with exactly n unit resistors.

Original entry on oeis.org

1, 1, 2, 4, 9, 23, 57, 151, 427, 1263, 3807, 11549, 34843, 104459, 311317, 928719, 2776247, 8320757, 24967341, 74985337
Offset: 0

Views

Author

Hugo Pfoertner and Rainer Rosenthal, Feb 14 2021

Keywords

Examples

			a(10) = 3807, whereas A337517(10) = 3823. The difference of 16 resistances results from the 15 terms of A338601/A338602 and the resistance 34/27 not representable by a planar network of 10 resistors, whereas it (but not 27/34) can be represented by a nonplanar network of 10 resistors.

Links

Crossrefs

Cf. A002840, A048211, A174283, A180414, A337516, A337517, A338511, A338601, A338602, A340921.
Cf. A113881, A219158.

Programs

Formula

a(n) = A337517(n) for n <= 9, a(n) < A337517(n) for n >= 10.

Extensions

a(19) from Hugo Pfoertner, Mar 15 2021

A199676 Number of minimally 3-connected non-isomorphic graphs on n vertices.

Original entry on oeis.org

1, 1, 3, 5, 18, 57, 285, 1513, 9824, 69536, 540622, 4494676
Offset: 4

Views

Author

N. J. A. Sloane, Nov 09 2011

Keywords

Links

Crossrefs

Cf. A006290, A204198, A324418, A338511.

Extensions

a(12) given by Jens M. Schmidt, Feb 27 2019
a(13)-a(15) from Jens M. Schmidt's web page, Jan 10 2021

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
Previous Showing 11-16 of 16 results.

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

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