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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A343873 Triangle read by rows: T(n,k) is the number of unlabeled connected planar graphs with n edges and k nodes (n >= 0, 1 <= k <= n + 1).

Original entry on oeis.org

1, 0, 1, 0, 0, 1, 0, 0, 1, 2, 0, 0, 0, 2, 3, 0, 0, 0, 1, 5, 6, 0, 0, 0, 1, 5, 13, 11, 0, 0, 0, 0, 4, 19, 33, 23, 0, 0, 0, 0, 2, 22, 67, 89, 47, 0, 0, 0, 0, 1, 19, 107, 236, 240, 106, 0, 0, 0, 0, 0, 13, 130, 486, 797, 657, 235, 0, 0, 0, 0, 0, 5, 130, 804, 2075, 2678, 1806, 551
Offset: 0

Views

Author

Andrew Howroyd, May 06 2021

Keywords

Comments

First differs from A054923 in row n=9.
Terms may be computed using the tools geng and planarg in nauty.

Examples

			Triangle begins (n edges >= 0, k vertices >= 1):
  1;
  0, 1;
  0, 0, 1;
  0, 0, 1, 2;
  0, 0, 0, 2, 3;
  0, 0, 0, 1, 5,  6;
  0, 0, 0, 1, 5, 13,  11;
  0, 0, 0, 0, 4, 19,  33,  23;
  0, 0, 0, 0, 2, 22,  67,  89,  47;
  0, 0, 0, 0, 1, 19, 107, 236, 240, 106;
  0, 0, 0, 0, 0, 13, 130, 486, 797, 657, 235;
  ...
		

Crossrefs

Row sums are A046091.
Column sums are A003094.
Main diagonal is A000055.
Subsequent diagonals are A001429, A001435, A001436 (same as for not necessarily planar graphs).
Cf. A049334 (transpose), A054923, A343870.

Programs

  • nauty
    geng -c $k $n:$n | planarg -q | countg -q # Georg Grasegger, Jul 06 2023

A049340 Triangle read by rows: T(n,k) is the number of planar graphs with n >= 1 nodes and 0 <= k <= binomial(n,2) edges, all degrees even.

Original entry on oeis.org

1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 3, 2, 2, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 3, 4, 4, 6, 5, 5, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 3, 4, 7, 9, 15, 17, 22, 14, 16, 5, 4, 0, 1, 0, 0, 0
Offset: 1

Views

Author

Keywords

Examples

			Triangle begins:
  1;
  1, 0;
  1, 0, 0, 1;
  1, 0, 0, 1, 1, 0, 0;
  1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0;
  1, 0, 0, 1, 1, 1, 3, 2, 2, 1, 1, 0, 1, 0, 0, 0;
  ...
		

Crossrefs

Rows sums give A049339.

Extensions

Entry revised by Sean A. Irvine, Jul 29 2021

A145270 Number of simple connected nonplanar graphs on n nodes.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 13, 207, 5143, 189195, 10663766, 989251266, 163746458178, 50329965610911
Offset: 0

Views

Author

Eric W. Weisstein, Oct 05 2008

Keywords

Crossrefs

Cf. A145269.

Formula

a(n) = A001349(n) - A003094(n).

Extensions

Edited by Max Alekseyev, Sep 18 2009
a(12) added by Max Alekseyev, Aug 17 2015
a(13) from Max Alekseyev, Feb 20 2025

A243321 Number of simple connected graphs with n nodes that are bipartite and planar.

Original entry on oeis.org

1, 1, 1, 3, 5, 16, 41, 158, 582, 2749, 13852, 80341, 503582, 3419670, 24533162, 184227017
Offset: 1

Views

Author

Travis Hoppe and Anna Petrone, Jun 03 2014

Keywords

Crossrefs

Cf. A003216 (bipartite graphs), A003094 (planar graphs).

Programs

  • Mathematica
    A164099 = Cases[Import["https://oeis.org/A164099/b164099.txt", "Table"], {, }][[All, 2]];
    (* EulerInvTransform is defined in A022562 *)
    EulerInvTransform[{0} ~Join~ A164099 + 1] (* Jean-François Alcover, Dec 03 2019, updated Mar 17 2020 *)

Formula

Inverse Euler transform of (A164099 + 1). - Falk Hüffner, May 10 2019

Extensions

a(11)-a(16) added using tinygraph by Falk Hüffner, May 10 2019

A298446 Triangle T(n,k) read by rows: number of n-node connected graphs with rectilinear crossing number k (k=0..A014540(n)).

Original entry on oeis.org

1, 1, 2, 6, 20, 1, 99, 11, 1, 1, 646, 149, 38, 15, 1, 2, 1, 0, 0, 1, 5974, 3008, 1251, 542, 171, 80, 47, 12, 15, 7, 4, 1, 3, 0, 0, 1, 0, 0, 0, 1, 71885
Offset: 1

Views

Author

Eric W. Weisstein, Jan 19 2018

Keywords

Comments

Computed up to n=8 using data provided by Geoffrey Exoo. (There appear to be some problems with n=9 data.)
T(9,1) >= 71335. - Eric W. Weisstein, Mar 28 2019

Examples

			Triangle begins:
1
1
2
6
20,1
99,11,1,1
646,149,38,15,1,2,1,0,0,1
5974,3008,1251,542,171,80,47,12,15,7,4,1,3,0,0,1,0,0,0,1
		

Crossrefs

Cf. A014540 (rectilinear crossing number for K_n).
Cf. A298445 (counts for simple graph).

Formula

T(n,0) = A003094(n).
kmax(n) = A014540(n).
T(n,kmax(n)) = 1 for n > 4.
sum(k=0..kmax(n), T(n,k)) = A001349(n).

Extensions

Corrected by Eric W. Weisstein, Mar 28 2019

A301425 Number of plane 5-regular simple connected graphs with 2n vertices.

Original entry on oeis.org

1, 0, 1, 1, 6, 14, 98, 529, 4035, 31009, 252386, 2073769, 17277113
Offset: 6

Views

Author

M. F. Hasler, Mar 20 2018

Keywords

Comments

We count here plane graphs, i.e., graphs embedded in the plane, up to embedding-preserving isomorphism, while such sequences as A003094 count planar graphs (counted up to abstract isomorphism). In this we follow the nomenclature of Brendan McKay, cf. link.

Examples

			There is only a(6) = 1 planar 5-regular simple connected graph with 2n = 12 vertices, which is the icosahedral graph, cf. MathWorld link. If we label the vertices 1, ..., 9, A, B, C, they are connected as follows: 1 -> {2 3 4 5 6}, 2 -> {1 6 7 8 3}, 3 -> {1 2 8 9 4}, 4 -> {1 3 9 A 5}, 5 -> {1 4 A B 6}, 6 -> {1 5 B 7 2 }, 7 -> {2 6 B C 8}, 8 -> {2 7 C 9 3}, 9 -> {3 8 C A 4}, A -> {4 9 C B 5}, B -> {5 A C 7 6}, C -> {7 B A 9 8}.
For other numbers of vertices, the number of plane 5-regular simple connected graphs is as follows:
14 vertices: 0  graphs,
16 vertices: 1  graph,
18 vertices: 1  graph,
20 vertices: 6  graphs,
22 vertices: 14  graphs,
24 vertices: 98  graphs,
26 vertices: 529  graphs,
28 vertices: 4035  graphs,
30 vertices: 31009  graphs,
32 vertices: 252386  graphs,
34 vertices: 2073769 graphs,
36 vertices: 17277113 graphs. (From the McKay web page.)
		

Crossrefs

A307072 Number of simple connected graphs on n nodes with crossing number 1.

Original entry on oeis.org

0, 0, 0, 0, 1, 11, 149, 3008, 71335, 1814021
Offset: 1

Views

Author

Eric W. Weisstein, Mar 22 2019

Keywords

Examples

			5-node: K_5.
6-node: includes K_{1,2,3}, (5-1)-lollipop, 2 X 3 queen, utility graph K_{3,3}.
		

Crossrefs

Cf. A307071 (not necessarily connected graphs).
Cf. A003094 (connected graphs with crossing number 0).

Extensions

a(9) from Eric W. Weisstein, Apr 17 2019
a(10) from Eric W. Weisstein, Apr 28 2019

A342213 Largest number of maximal planar node-induced subgraphs of an n-node graph.

Original entry on oeis.org

1, 1, 1, 1, 5, 15, 35, 70, 126, 211
Offset: 1

Views

Author

Pontus von Brömssen, Mar 05 2021

Keywords

Comments

This sequence is log-superadditive, i.e., a(m+n) >= a(m)*a(n). By Fekete's subadditive lemma, it follows that the limit of a(n)^(1/n) exists and equals the supremum of a(n)^(1/n). - Pontus von Brömssen, Mar 03 2022
a(11) >= 381, because the complete 5-partite graph K_{1,1,3,3,3} has 381 maximal planar subgraphs.

Examples

			For 4 <= n <= 9, a(n) = binomial(n,4) = A000332(n) and the complete graph is optimal, but a(10) = 211 > 210 = binomial(10,4) with the optimal graph being the complete 6-partite graph K_{1,1,1,1,3,3}. The optimal graph is unique when 5 <= n <= 10.
		

Crossrefs

For a list of related sequences, see cross-references in A342211.

Formula

a(m+n) >= a(m)*a(n).
Lim_{n->oo} a(n)^(1/n) >= 381^(1/11) = 1.71644... .

A361368 Number of weakly connected simple planar digraphs with n unlabeled nodes.

Original entry on oeis.org

2, 13, 199, 8782, 897604
Offset: 2

Views

Author

Manfred Scheucher, Mar 09 2023

Keywords

References

  • M. Kirchweger, M. Scheucher, and S. Szeider, SAT-Based Generation of Planar Graphs, in preparation.

Crossrefs

Directed variant of A003094.

A361578 Number of 5-connected polyhedra (or 5-connected simple planar graphs) with n nodes.

Original entry on oeis.org

1, 0, 1, 1, 5, 8, 30, 85, 382, 1550, 7352
Offset: 12

Views

Author

Manfred Scheucher, Mar 16 2023

Keywords

Comments

The icosahedral graph is the smallest 5-connected planar graph.

References

  • M. Kirchweger, M. Scheucher, and S. Szeider, SAT-Based Generation of Planar Graphs, in preparation.

Crossrefs

Cf. A049373 (planar graphs with minimum degree~5) and A111358 (5-connected planar trianguations)
Previous Showing 11-20 of 28 results. Next