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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A005964 Number of trivalent connected (or cubic) planar graphs with 2n nodes.

Original entry on oeis.org

0, 1, 1, 3, 9, 32, 133, 681, 3893, 24809, 169206, 1214462, 9034509, 69093299, 539991437
Offset: 1

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Author

Keywords

References

  • A. T. Balaban, Enumeration of Cyclic Graphs, pp. 63-105 of A. T. Balaban, ed., Chemical Applications of Graph Theory, Ac. Press, 1976; see p. 92.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Extensions

Extended by Brendan McKay and Gunnar Brinkmann using their program "plantri", Dec 19 2000

A002880 Number of 3-connected nets with n edges.

Original entry on oeis.org

1, 0, 1, 1, 2, 2, 9, 11, 37, 79, 249, 671, 2182, 6692, 22131, 72405, 243806, 822788, 2815119, 9679205, 33551192, 116900081, 409675567, 1442454215, 5102542680, 18124571838, 64634480340, 231334873091, 830828150081, 2993489821771
Offset: 6

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Keywords

Comments

Also, the number of 3-connected quadrangulations without separating 4-cycles (up to orientation) with n faces. - Andrey Zabolotskiy, Sep 20 2019

Examples

			G.f. = x^6 + x^8 + x^9 + 2*x^10 + 2*x^11 + 9*x^12 + 11*x^13 + 37*x^14 + ...
		

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

A113201 Number of isomorphism classes of simple quadrangulations of the sphere having n vertices and n-2 faces, with orientation-reversing isomorphisms permitted.

Original entry on oeis.org

1, 1, 2, 3, 9, 18, 62, 198, 803, 3378, 15882, 77185, 393075, 2049974, 10938182, 59312272, 326258544, 1815910231, 10213424233, 57974895671, 331820721234, 1913429250439, 11109119321058, 64901418126997
Offset: 4

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Author

N. J. A. Sloane, Jan 07 2006

Keywords

Crossrefs

A081621 Number of n-node triangulations of the sphere with minimal degree 5.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 3, 4, 12, 23, 73, 192, 651, 2070, 7290, 25381, 91441, 329824, 1204737, 4412031, 16248772, 59995535, 222231424, 825028656, 3069993552, 11446245342, 42758608761, 160012226334, 599822851579, 2252137171764, 8469193859271, 31896058068930
Offset: 4

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Author

Hugo Pfoertner, Mar 24 2003

Keywords

Comments

Other face sizes larger than 5 and 6 are allowed and there can be more than 12 vertices with degree 5.
Convex polytopes with minimum degree at least 5. The sequence is extracted from the file more-counts.txt that comes with the plantri distribution.
Grace conjectured that all polyhedra inscribed in the unit sphere with maximal volume are "medial" (all faces triangular and vertex degree either m or m+1 where m < 6 - 12/n < m+1). For n = 12 and n > 13 the medial polyhedra have 12 vertices of degree 5 and n-12 vertices of degree 6. All known numerical solutions of the maximal volume problem (A081314) have this property.
The triangulated arrangements of points on a sphere with icosahedral symmetry given by Hardin, Sloane and Smith are examples for large n.

Examples

			With vertices denoted by letters a, b, ... the neighbor lists are for a(14)=1: (bcdef, afghc, abhid, acije, adjkf, aeklgb, bflmh, bgmic, chmnjd, dinke, ejnlf, fknmg, glnih, imlkj).
a(15)=1: (bcdefg, aghic, abijd, acjke, adklf, aelmg, afmhb, bgmni, bhnjc, cinokd, djole, ekomf, flonhg, hmoji, jnmlk); a(16)=3: (bcdef, afghc, abhijd, acjke, adklf, aelmgb, bfmnh, bgnic, chnoj, ciokd, djople, ekpmf, flpng, gmpoih, inpkj, konml), (bcdef, afghc, abhijd, acjke, adklf, aelmgb, bfmnh, bgnic, chnoj, ciopkd, djple, ekpmf, flpong, gmoih, inmpj, jomlk), (bcdef, afghijc, abjkd, ackle, adlmf, aemgb, bfmnh, bgnoi, bhopj, bipkc, cjpld, dkponme, elngf, gmloh, hnlpi, iolkj).
		

Crossrefs

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 05 2007
a(41) computed with plantri by Jan Goedgebeur, Dec 03 2021

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

A113204 Same as A007022, but with orientation-reversing isomorphisms forbidden.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 1, 1, 4, 3, 15, 25, 92, 234, 803, 2469, 8512, 28290, 98148, 338673, 1188338, 4180854, 14840031, 52904562, 189724510, 683384218, 2472961423, 8984888982, 32772085447, 119963084542, 440623586740, 1623555117611
Offset: 1

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Author

N. J. A. Sloane, Jan 07 2006

Keywords

Crossrefs

Extensions

a(29) corrected by Brendan McKay, Jun 22 2006
Leading zeros prepended by Max Alekseyev, Sep 13 2016
Offset corrected by Andrey Zabolotskiy, Feb 09 2018

A113205 Same as A002880, but with orientation-reversing isomorphisms forbidden.

Original entry on oeis.org

1, 0, 1, 1, 3, 2, 12, 16, 59, 133, 445, 1248, 4162, 13014, 43474, 143304, 484444, 1639388, 5617205, 19332596, 67048051, 233691112, 819121608, 2884443024, 10204104900, 36247138920, 129264732757, 462661038926, 1661637913984
Offset: 6

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Author

N. J. A. Sloane, Jan 07 2006

Keywords

Crossrefs

A058378 Number of trivalent 2-connected planar graphs with 2n nodes.

Original entry on oeis.org

0, 1, 1, 3, 8, 29, 114, 583, 3310, 21168, 144622, 1039495, 7731540
Offset: 1

Views

Author

N. J. A. Sloane, Dec 19 2000

Keywords

References

  • A. T. Balaban, Enumeration of Cyclic Graphs, pp. 63-105 of A. T. Balaban, ed., Chemical Applications of Graph Theory, Ac. Press, 1976; see p. 92.
  • Computed by Brendan McKay and Gunnar Brinkmann using their program "plantri", Dec 19 2000.

Crossrefs

A113202 Number of isomorphism classes of simple quadrangulations of the sphere having n vertices and n-2 faces, with orientation-reversing isomorphisms forbidden.

Original entry on oeis.org

1, 1, 2, 3, 10, 21, 83, 298, 1339, 6049, 29765, 148842, 770267, 4054539, 21743705, 118237471, 651370528, 3628421181, 20416662314, 115919209155, 663548898942, 3826577783917, 22217382001865, 129800215435088
Offset: 4

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Author

N. J. A. Sloane, Jan 07 2006

Keywords

Crossrefs

A113203 Number of isomorphism classes of simple quadrangulations of the sphere having n vertices and n-2 faces, minimal degree 3, with orientation-reversing isomorphisms forbidden.

Original entry on oeis.org

1, 0, 1, 1, 4, 3, 16, 26, 99, 256, 895, 2789, 9740, 32799, 115024, 401180, 1421170, 5046539, 18066772, 64940825, 234712099, 851801048, 3104690139, 11358900851, 41710948878, 153684688127, 568079430741, 2106188450292
Offset: 8

Views

Author

N. J. A. Sloane, Jan 07 2006

Keywords

Crossrefs

Previous Showing 11-20 of 25 results. Next