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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A007030 Non-Hamiltonian simplicial polyhedra with n nodes.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 30, 239, 2369, 22039, 205663, 1879665, 16999932, 152227187, 1353996482
Offset: 1

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Author

Keywords

Comments

a(18) = 1879665 was conjectured by Dillencourt and verified by direct computation by Sean A. Irvine, Sep 26 2017.
By Steinitz's theorem non-Hamiltonian simplicial polyhedra correspond to non-Hamiltonian maximal planar graphs. - William P. Orrick, Feb 25 2021

Examples

			The unique non-Hamiltonian maximal planar graph of 11 vertices is the Goldner-Harary graph. A corresponding simplicial polyhedron can be obtained by attaching a tetrahedron to each of the six faces of a triangular bipyramid. - _William P. Orrick_, Feb 25 2021
		

References

  • M. B. Dillencourt, Polyhedra of small orders and their Hamiltonian properties. Tech. Rep. 92-91, Info. and Comp. Sci. Dept., Univ. Calif. Irvine, 1992.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Formula

a(n) = A000109(n) - A115340(n-2). - William P. Orrick, Feb 20 2021

Extensions

a(18) from Sean A. Irvine, Sep 26 2017
a(19)-a(21) using new formula by William P. Orrick, Feb 20 2021

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

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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

A115340 Number of dual Hamiltonian cubic polyhedra or planar 3-connected Yutsis graphs on 2n nodes.

Original entry on oeis.org

1, 1, 2, 5, 14, 50, 233, 1248, 7593, 49536, 339483, 2404472, 17468202, 129459090, 975647292, 7458907217, 57744122366, 452028275567, 3573870490382
Offset: 2

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Author

Dries Van Dyck (VanDyck.Dries(AT)gmail.com), Mar 06 2006

Keywords

Comments

Also, a(n) is the number of Hamiltonian planar triangulations with n+2 vertices. - Brendan McKay, Feb 20 2021
Yutsis graphs are connected cubic graphs which can be partitioned into two vertex-induced trees, which are necessarily of the same size. The cut separating both trees contains n+2 edges for a graph on 2n nodes, forming a Hamiltonian cycle in the planar dual if the graph is planar. These graphs are maximal in the number of nodes of the largest vertex-induced forests among the connected cubic graphs (floor((6n-2)/4) for a graph on 2n nodes). Whitney showed in 1931 that proving the 4-color theorem for a planar Yutsis graph implies the theorem for all planar graphs.

References

  • F. Jaeger, On vertex induced-forests in cubic graphs, Proceedings 5th Southeastern Conference, Congressus Numerantium (1974) 501-512.

Crossrefs

Programs

Formula

a(n) = A000109(n+2) - A007030(n+2). - William P. Orrick, Feb 20 2021

Extensions

a(20) from Van Dyck et al. added by Andrey Zabolotskiy, Sep 10 2024

A253882 Number of 3-connected planar triangulations of the sphere with n vertices up to orientation preserving isomorphisms.

Original entry on oeis.org

1, 1, 2, 6, 17, 73, 389, 2274, 14502, 97033, 672781, 4792530, 34911786, 259106122, 1954315346, 14949368524, 115784496932, 906736988527, 7171613842488, 57231089062625, 460428456484557, 3731572377382341, 30447133566946517, 249968326771680542, 2063931874299323140
Offset: 4

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Author

Danny Rorabaugh, Feb 27 2015

Keywords

Crossrefs

Cf. A000109 (full automorphism group), A000260 (rooted at an edge), A000944, A002709 (with a distinguished face).

Programs

  • PARI
    a(n)={if(n<3, 0, (2*binomial(4*(n-3)+1, n-3)/((n-2)*(3*n-7))
      + 3*sumdiv(n-2, d, if(d>=2, my(s=(n-2)/d); eulerphi(d)*binomial(4*s,s))/4)
      + if(n%2==1, my(s=(n-3)/2); 3*binomial(4*s,s)*(2*s+1)/(3*s+1))
      + if(n%3==1, my(s=(n-4)/3); 8*binomial(4*s,s)*(4*s+1)/(3*s+1))
      + if(n%3==0, my(s=(n-3)/3); 2*binomial(4*s,s)) )/(6*(n-2)))} \\ Andrew Howroyd, Mar 02 2021

Extensions

Name clarified and terms a(24) and beyond from Andrew Howroyd, Mar 02 2021

A133236 Number of bipartite planar graphs with 2n nodes and at least one zero eigenvector.

Original entry on oeis.org

0, 1, 0, 1, 11, 8, 70, 613, 1225, 11330, 120628
Offset: 2

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Author

N. J. A. Sloane, Oct 14 2007

Keywords

References

  • Sciriha, I. and Fowler, P.W., Nonbonding Orbitals in Fullerenes: Nuts and Cores in Singular Polyhedral Graphs J. Chem. Inf. Model., 47, 5, 1763 - 1775, 2007.

Crossrefs

A133237 Number of bipartite planar graphs with 2n nodes and exactly one zero eigenvector.

Original entry on oeis.org

0, 0, 0, 1, 2, 7, 67, 322, 1123, 10548, 81127
Offset: 2

Views

Author

N. J. A. Sloane, Oct 14 2007

Keywords

References

  • Sciriha, I. and Fowler, P.W., Nonbonding Orbitals in Fullerenes: Nuts and Cores in Singular Polyhedral Graphs J. Chem. Inf. Model., 47, 5, 1763 - 1775, 2007.

Crossrefs

A222318 Number of 4-dimensional simplicial convex polytopes with n nodes.

Original entry on oeis.org

1, 2, 5, 37, 1142, 162004
Offset: 5

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Author

N. J. A. Sloane, Feb 16 2013

Keywords

Crossrefs

Extensions

Changed "4" to "n" in description of sequence. - Moritz Firsching, Apr 02 2015
a(10) from M. Firsching's paper added by Andrey Zabolotskiy, Jun 28 2022

A342971 Non-1-tough simplicial polyhedra with n nodes.

Original entry on oeis.org

1, 2, 29, 233, 2297, 21192, 195862
Offset: 11

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Author

William P. Orrick, Apr 01 2021

Keywords

Comments

A graph is 1-tough if there is no set of k vertices whose deletion splits the graph into more than k components.
If a graph is not 1-tough then it is not Hamiltonian.

Crossrefs

Formula

a(n) = A007030(n) - A007031(n).

A007020 Maximal planar degree sequences with n nodes.

Original entry on oeis.org

1, 1, 1, 2, 5, 13, 33, 85, 199, 445, 947, 1909, 3713, 7006, 12765, 22764, 39540
Offset: 3

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Author

Keywords

Comments

The number of distinct degree sequences occurring in the polyhedra counted by A000109. - Sean A. Irvine, Sep 17 2017

References

  • M. B. Dillencourt, Polyhedra of small orders and their Hamiltonian properties. Tech. Rep. 92-91, Info. and Comp. Sci. Dept., Univ. Calif. Irvine, 1992.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A000109.

Extensions

a(17)-a(19) from Sean A. Irvine, Sep 17 2017

A058789 Number of polyhedra with n faces and n+1 vertices (or n vertices and n+1 faces).

Original entry on oeis.org

0, 1, 2, 11, 74, 633, 6134, 64439, 709302, 8085725, 94713809, 1134914458, 13865916560, 172301697581, 2173270387051
Offset: 4

Views

Author

Gerard P. Michon, Nov 30 2000

Keywords

Comments

Through a(18) the only primes are 2, 11, and 64439. - Jonathan Vos Post, Apr 23 2011

Examples

			a(5)=1 because the triangular prism is the only pentahedron with 6 vertices.
		

Crossrefs

Previous Showing 11-20 of 25 results. Next