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.

A122661 Erroneous version of A007894.

Original entry on oeis.org

6, 15, 17, 40, 49, 89, 116, 199, 271, 437, 580, 924, 1205, 1812, 2385, 3465, 4478, 6332, 8149, 11190, 14246
Offset: 17

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Author

Keywords

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

A046880 Number of isolated-pentagon (IPR) fullerenes with 2n vertices (or carbon atoms).

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 1, 2, 5, 7, 9, 24, 19, 35, 46, 86, 134, 187, 259, 450, 616, 823, 1233, 1799, 2355, 3342, 4468, 6063, 8148, 10774, 13977, 18769, 23589, 30683, 39393, 49878, 62372, 79362, 98541, 121354, 151201, 186611, 225245, 277930, 335569
Offset: 30

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Author

Gunnar Brinkmann and A. Dress (dress(AT)mathematik.uni-bielefeld.de)

Keywords

Comments

Enantiomorphic pairs are regarded as the same here. Cf. A086423.

References

  • P. W. Fowler and D. E. Manolopoulos, An Atlas of Fullerenes, Cambridge Univ. Press, 1995, see p. 33.

Crossrefs

Extensions

Added a(121)-a(200). a(30)-a(190) is independently confirmed by buckygen and fullgen, while a(191)-a(200) was only computed by buckygen. - Jan Goedgebeur, Aug 08 2012

A057210 Number of fullerenes with 2n vertices (or carbon atoms), counting enantiomorphic pairs as distinct.

Original entry on oeis.org

1, 0, 1, 1, 3, 3, 10, 9, 23, 30, 66, 80, 162, 209, 374, 507, 835, 1113, 1778, 2344, 3532, 4670, 6796, 8825, 12501, 16091, 22142, 28232, 38016, 47868, 63416, 79023, 102684, 126973, 162793, 199128, 252082, 306061, 382627, 461020
Offset: 10

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Author

N. J. A. Sloane, Aug 28 2003

Keywords

References

  • P. W. Fowler and D. E. Manolopoulos, An Atlas of Fullerenes, Cambridge Univ. Press, 1995, see p. 32.

Crossrefs

Formula

a(n) = (809/1306069401600)*sigma_9(n) + O(n^8) where sigma_9(n) is the ninth divisor power sum, A013957. - Philip Engel, Nov 29 2017

A111358 Numbers of planar triangulations with minimum degree 5 and without separating 3- or 4-cycles - that is 3- or 4-cycles where the interior and exterior contain at least one vertex.

Original entry on oeis.org

1, 0, 1, 1, 3, 4, 12, 23, 71, 187, 627, 1970, 6833, 23384, 82625, 292164, 1045329, 3750277, 13532724, 48977625, 177919099, 648145255, 2368046117, 8674199554, 31854078139, 117252592450, 432576302286, 1599320144703, 5925181102878
Offset: 12

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Author

Gunnar Brinkmann, Nov 07 2005

Keywords

Comments

A006791 and this sequence are the same sequence. The correspondence is just that these objects are planar duals of each other. But the offset and step are different: if the cubic graph has 2*n vertices, the dual triangulation has n+2 vertices. - Brendan McKay, May 24 2017
Also the number of 5-connected triangulations on n vertices. - Manfred Scheucher, Mar 17 2023

Examples

			The icosahedron is the smallest triangulation with minimum degree 5 and it doesn't contain any separating 3- or 4-cycles. Examples can easily be seen as 2D and 3D pictures using the program CaGe cited above.
		

Crossrefs

A086423 Number of isolated-pentagon fullerenes with 2n vertices (or carbon atoms).

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 1, 3, 6, 9, 12, 34, 33, 56, 78, 161, 252, 349, 483, 862, 1179, 1606, 2401, 3502, 4645, 6568, 8820, 11997, 16132, 21326, 27763, 37313, 46907, 61069, 78476, 99343, 124282, 158258, 196532, 242126, 301752, 372498, 449742
Offset: 30

Views

Author

N. J. A. Sloane, Sep 08 2003

Keywords

Comments

Enantiomorphic pairs are counted as different here. Cf. A046880.

References

  • P. W. Fowler and D. E. Manolopoulos, An Atlas of Fullerenes, Cambridge Univ. Press, 1995, see p. 33.

Crossrefs

Extensions

More terms from Gunnar Brinkmann, Aug 24 2006

A111357 Numbers of planar triangulations with minimum degree 5 and without separating 3-cycles - that is 3-cycles where the interior and exterior contain at least one vertex.

Original entry on oeis.org

1, 0, 1, 1, 3, 4, 12, 23, 73, 191, 649, 2054, 7209, 24963, 89376, 320133, 1160752, 4218225, 15414908, 56474453, 207586410, 764855802, 2825168619, 10458049611, 38795658003, 144203518881, 537031911877, 2003618333624, 7488436558647
Offset: 12

Views

Author

Gunnar Brinkmann, Nov 07 2005

Keywords

Examples

			The icosahedron is the smallest triangulation with minimum degree 5 and it doesn't contain any separating triangles. Examples can easily be seen as 2D and 3D pictures using the program CaGe cited above.
		

Crossrefs

Showing 1-7 of 7 results.