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 1-7 of 7 results.

A111361 The number of 4-regular plane graphs with n vertices with all faces 3-gons or 4-gons.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 1, 1, 2, 1, 5, 2, 8, 5, 12, 8, 25, 13, 30, 23, 51, 33, 76, 51, 109, 78, 144, 106, 218, 150, 274, 212, 382, 279, 499, 366, 650, 493, 815, 623, 1083, 800, 1305, 1020, 1653, 1261, 2045, 1554, 2505, 1946, 3008, 2322, 3713, 2829, 4354, 3418, 5233, 4063, 6234
Offset: 2

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Author

Gunnar Brinkmann, Nov 07 2005

Keywords

Comments

These are the 4-regular graphs corresponding to the 3-regular fullerenes. Only the two smallest possible face sizes are allowed. The numbers up to a(33) have been checked by 2 independent programs. Further numbers have not been checked independently.

Examples

			From _Allan Bickle_, May 13 2024: (Start)
The smallest example (n=6) is the octahedron (only 3-gons).
For n=8, the unique graph is the square of an 8-cycle.
For n=9, the unique graph is the dual of the Herschel graph. (End)
		

Crossrefs

Cf. A007894.
Cf. A007022, A072552, A078666, A292515 (4-regular planar graphs with restrictions).

Extensions

Leading zeros prepended, terms a(34) and beyond added from the book by Deza et al. (except for a(60) from the paper by Brinkmann et al.) by Andrey Zabolotskiy, Oct 09 2021

A167156 Number of n-vertex 4-hedrites.

Original entry on oeis.org

1, 0, 2, 0, 2, 0, 4, 0, 3, 0, 5, 0, 3, 0, 7, 0, 5, 0, 7, 0, 4, 0, 11, 0, 5, 0, 8, 0, 8, 0, 12, 0, 6, 0, 13, 0, 6, 0, 15, 0, 10, 0, 11, 0, 7, 0, 21, 0, 10, 0, 13, 0, 12, 0, 18, 0, 9, 0, 22, 0, 9, 0, 21, 0, 14, 0, 16, 0, 14
Offset: 2

Views

Author

Jonathan Vos Post, Oct 29 2009

Keywords

Comments

Is this the same as A145393 alternating with zeros? - Andrey Zabolotskiy, Jul 05 2017

Examples

			Although every other term is zero, this sequence should be kept, contrary to the usual OEIS rules, to be analogous to the related sequences.
		

Crossrefs

A167159 Number of n-vertex 7-hedrites.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 1, 1, 3, 4, 5, 7, 9, 12, 18, 22, 25, 36, 46, 48, 62, 76, 88, 107, 126, 142, 179, 198, 216, 257, 304, 329, 382, 431, 483, 547, 601, 643, 764, 838, 889, 998, 1134, 1197, 1324, 1435, 1574, 1751, 1874, 1963, 2247, 2419, 2511, 2735, 3041, 3187, 3453
Offset: 2

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Author

Jonathan Vos Post, Oct 29 2009

Keywords

Comments

A k-hedrite is a 4-regular planar graph whose faces have sizes 2, 3 and 4 only and the total number of faces of sizes 2 and 3 is k.

Crossrefs

Extensions

New name from Andrey Zabolotskiy, Jul 05 2017

A167157 Number of n-vertex 5-hedrites.

Original entry on oeis.org

0, 1, 0, 1, 2, 3, 1, 2, 3, 5, 3, 4, 7, 10, 6, 6, 7, 12, 9, 8, 15, 20, 11, 12, 16, 21, 18, 16, 24, 32, 24, 18, 26, 37, 23, 24, 38, 45, 37, 30, 33, 52, 44, 34, 56, 69, 45, 40, 54, 66, 58, 48, 66, 92, 68, 49, 71, 98, 70, 63, 96, 104, 92, 74, 80, 122, 98, 72, 120
Offset: 2

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Author

Jonathan Vos Post, Oct 29 2009

Keywords

Comments

A k-hedrite is a 4-regular planar graph whose faces have sizes 2, 3 and 4 only and the total number of faces of sizes 2 and 3 is k.

Crossrefs

Extensions

New name from Andrey Zabolotskiy, Jul 05 2017

A167227 Number of 2-self-hedrites with n vertices.

Original entry on oeis.org

1, 1, 2, 2, 3, 3, 3, 3, 5, 4, 4, 6, 5, 5, 8, 5, 6, 8, 6, 8, 10, 7, 7, 10, 10, 8, 12, 10, 9, 14, 9, 9, 14, 10, 14, 16, 11, 11, 16
Offset: 2

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Author

Jonathan Vos Post, Oct 30 2009

Keywords

Comments

A 2-self-hedrite is a self-dual plane multigraph such that each its face has 4 sides except for 2 faces with 2 sides. - Andrey Zabolotskiy, Dec 16 2021

Crossrefs

Formula

It appears that a(n+1) = A167156(2*n) - A167156(n) [discovered using Sequence Machine]. An equivalent assertion is that if a plane multigraph and its dual both have only 4-gonal faces except for 2 2-gonal ones, then they are isomorphic. - Andrey Zabolotskiy, Dec 16 2021

A167228 Number of 3-self-hedrites with n vertices.

Original entry on oeis.org

0, 1, 1, 4, 6, 7, 11, 16, 16, 26, 29, 30, 42, 47, 48, 64, 72, 70, 89, 104, 90, 119, 131, 124, 162, 170, 158, 190, 210, 202, 239, 256, 232, 290, 308, 286, 342, 359, 332
Offset: 2

Views

Author

Jonathan Vos Post, Oct 30 2009

Keywords

Crossrefs

A167229 Number of 4-self-hedrites with n vertices.

Original entry on oeis.org

0, 0, 1, 1, 2, 4, 6, 8, 15, 16, 24, 33, 40, 48, 69, 73, 92, 114, 130, 148, 191, 198, 234, 276, 304, 332, 407, 421, 476, 550, 584, 631, 748, 760, 857, 956, 1002, 1070, 1239
Offset: 2

Views

Author

Jonathan Vos Post, Oct 30 2009

Keywords

Crossrefs

Showing 1-7 of 7 results.