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 1-10 of 29 results. Next

A262391 Erroneous duplicate of A000944.

Original entry on oeis.org

0, 0, 0, 1, 2, 6, 34, 257, 2606, 440564, 6384634, 96262938, 1496225352, 23833988129, 387591510244, 6415851530241, 107854282197058
Offset: 1

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Author

Jiazhen Tan, Sep 21 2015

Keywords

Examples

			For n=4 the only possible shape is a tetrahedron with four triangle sides.
For n=5 the only possible shapes are the square pyramid and triangular prism.
		

A000109 Number of simplicial polyhedra with n vertices; simple planar graphs with n vertices and 3n-6 edges; maximal simple planar graphs with n vertices; planar triangulations with n vertices; triangulations of the sphere with n vertices; 3-connected cubic planar graphs on 2n-4 vertices.

Original entry on oeis.org

1, 1, 1, 2, 5, 14, 50, 233, 1249, 7595, 49566, 339722, 2406841, 17490241, 129664753, 977526957, 7475907149, 57896349553, 453382272049, 3585853662949, 28615703421545
Offset: 3

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Author

Keywords

Comments

Every planar triangulation on n >= 4 vertices is 3-connected (the connectivity either 3, 4, or 5) and its dual graph is a 3-connected cubic planar graph on 2n-4 vertices. - Manfred Scheucher, Mar 17 2023

References

  • G. Brinkmann and Brendan McKay, in preparation. [Looking at http://users.cecs.anu.edu.au/~bdm/publications.html, there are a few papers with Brinkmann that seem relevant, in particular #126 but also #97, 81, 158. Perhaps the right one is 126.]
  • M. B. Dillencourt, Polyhedra of small orders and their Hamiltonian properties. Tech. Rep. 92-91, Info. and Comp. Sci. Dept., Univ. Calif. Irvine, 1992.
  • C. F. Earl and L. J. March, Architectural applications of graph theory, pp. 327-355 of R. J. Wilson and L. W. Beineke, editors, Applications of Graph Theory. Academic Press, NY, 1979.
  • B. Grünbaum, Convex Polytopes. Wiley, NY, 1967, p. 424.
  • 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

Formula

From William P. Orrick, Apr 07 2021: (Start)
a(n) >= A007816(n-3)/n! = binomial(n,2)*(4*n-11)!/(n!*(3*n-6)!) for all n >= 4.
a(n) ~ A007816(n-3)/n! = binomial(n,2)*(4*n-11)!/(n!*(3*n-6)!) ~ (1/64)*sqrt(1/(6*Pi))*n^(-7/2)*(256/27)^(n-2), using the theorem that the automorphism group of a maximal planar graph is almost certainly trivial as n gets large. (Tutte)
(End)

Extensions

Extended by Brendan McKay and Gunnar Brinkmann using their program "plantri", Dec 19 2000
Definition clarified by Manfred Scheucher, Mar 17 2023

A002840 Number of polyhedral graphs with n edges.

Original entry on oeis.org

1, 0, 1, 2, 2, 4, 12, 22, 58, 158, 448, 1342, 4199, 13384, 43708, 144810, 485704, 1645576, 5623571, 19358410, 67078828, 233800162, 819267086, 2884908430, 10204782956, 36249143676, 129267865144, 462669746182, 1661652306539, 5986979643542
Offset: 6

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Author

Keywords

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, 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).
  • T. R. S. Walsh, personal communication.

Crossrefs

Programs

  • PARI
    \\ It is assumed that the 3cp.gp file (from the linked zip archive) has been read before, i.e., \r [path]3cp.gp
    for(k=6,#ThreeConnectedData,print1(#ThreeConnectedData[k],", "));
    \\ printing of the edge lists of the graphs for n <= 11
    print(ThreeConnectedData[6..11]) \\ Hugo Pfoertner, Feb 14 2021

Extensions

a(30)-a(35) from the Numericana link added by Andrey Zabolotskiy, Jun 13 2020

A007022 Number of 4-regular polyhedra with n nodes.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 1, 1, 3, 3, 11, 18, 58, 139, 451, 1326, 4461, 14554, 49957, 171159, 598102, 2098675, 7437910, 26490072, 94944685, 341867921, 1236864842, 4493270976, 16387852863, 59985464681, 220320405895, 811796327750, 3000183106119
Offset: 1

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Author

N. J. A. Sloane, Apr 28 1994

Keywords

Comments

Number of simple 4-regular 4-edge-connected 3-connected planar graphs; by Steinitz's theorem, every such graph corresponds to a single planar map up to orientation-reversing isomorphism. Equivalently, number of 3-connected quadrangulations of sphere with orientation-reversing isomorphisms permitted with n faces. - Andrey Zabolotskiy, Aug 22 2017

Examples

			For n=6, the sole 6-vertex 4-regular polyhedron is the octahedron. The corresponding 6-face quadrangulation is its dual graph, i. e., the cube graph.
From _Allan Bickle_, May 13 2024: (Start)
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)
		

References

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

Crossrefs

Cf. A000944 (all polyhedral graphs), A113204, A078672, A078666 (total number of simple 4-regular 4-edge-connected planar maps, including not 3-connected ones).
Cf. A072552, A078666, A111361, A292515 (4-regular planar graphs with restrictions).

Extensions

More terms from Hugo Pfoertner, Mar 22 2003
a(29) corrected by Brendan McKay, Jun 22 2006
Leading zeros prepended by Max Alekseyev, Sep 12 2016
Offset corrected by Andrey Zabolotskiy, Aug 22 2017

A279019 Least possible number of diagonals of simple convex polyhedron with n faces.

Original entry on oeis.org

0, 0, 2, 6, 12, 20, 30, 42, 56, 72, 90, 110, 132, 156, 182, 210, 240, 272, 306, 342, 380, 420, 462, 506, 552, 600, 650, 702, 756, 812, 870, 930, 992, 1056, 1122, 1190, 1260, 1332, 1406, 1482, 1560, 1640, 1722, 1806, 1892, 1980, 2070, 2162, 2256, 2352, 2450
Offset: 4

Views

Author

Vladimir Letsko, Dec 03 2016

Keywords

Comments

Obviously, a pyramid has no diagonals. Hence minimum of diagonals of an arbitrary convex polyhedron having n faces is equal to 0.
Minimum number of diagonals among simple convex polyhedra having n faces is obtained from a polyhedron with two triangular faces, n-4 quadrangular faces and two (n-1)-sided faces. A polyhedron having 3 triangular faces, 3 pentagonal faces and 1 hexagonal face gives another example of a simple convex polyhedron with the least possible number of diagonals for n = 7. A polyhedron having 4 triangular faces and 4 hexagonal faces gives a similar example for n = 8.
Essentially the same as A103505 and A002378. - R. J. Mathar, Dec 05 2016

Crossrefs

Programs

  • Mathematica
    Table[(n-4)(n-5),{n,4,60}] (* or *) LinearRecurrence[{3,-3,1},{0,0,2},60] (* Harvey P. Dale, Sep 23 2019 *)
  • PARI
    concat(vector(2), Vec(2*x^6 / (1 - x)^3 + O(x^60))) \\ Colin Barker, Dec 05 2016

Formula

a(n) = n^2 - 9*n + 20 = (n-4)*(n-5).
G.f.: -2*x^6/(x-1)^3. - R. J. Mathar, Dec 05 2016
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>6. - Colin Barker, Dec 05 2016
E.g.f.: exp(x)*(20 - 8*x + x^2) - x^3/3 - 3*x^2 - 12*x - 20. - Stefano Spezia, Nov 24 2019
From Amiram Eldar, Jul 09 2023: (Start)
Sum_{n>=6} 1/a(n) = 1.
Sum_{n>=6} (-1)^n/a(n) = 2*log(2) - 1. (End)

A212438 Irregular triangle read by rows: T(n,k) is the number of polyhedra with n faces and k vertices (n >= 4, k=4..2n-4).

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 2, 2, 2, 0, 0, 2, 8, 11, 8, 5, 0, 0, 2, 11, 42, 74, 76, 38, 14, 0, 0, 0, 8, 74, 296, 633, 768, 558, 219, 50, 0, 0, 0, 5, 76, 633, 2635, 6134, 8822, 7916, 4442, 1404, 233, 0, 0, 0, 0, 38, 768, 6134, 25626, 64439, 104213, 112082, 79773, 36528, 9714, 1249
Offset: 4

Views

Author

N. J. A. Sloane, May 16 2012

Keywords

Comments

Because of duality, T(n,k) = T(k,n). - Ivan Neretin, May 25 2016
The number of edges is n+k-2. - Andrew Howroyd, Mar 27 2021

Examples

			Triangle begins:
1
0 1 1
0 1 2  2  2
0 0 2  8 11   8    5
0 0 2 11 42  74   76   38   14
0 0 0  8 74 296  633  768  558  219   50
0 0 0  5 76 633 2635 6134 8822 7916 4442 1404 233
...
		

Crossrefs

A049337, A058787, A212438 are all versions of the same triangle.
Row sums (the same as column sums) are A000944.
Main diagonal is A002856.
Cf. A002840 (by edges), A239893.

Extensions

Terms a(53) and beyond from Andrew Howroyd, Mar 27 2021

A060296 Number of regular convex polytopes in n-dimensional space, or -1 if the number is infinite.

Original entry on oeis.org

1, 1, -1, 5, 6, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3
Offset: 0

Views

Author

Ahmed Fares (ahmedfares(AT)my-deja.com), Mar 24 2001

Keywords

Examples

			a(2) = -1 because of the regular polygons in the plane.
a(3) = 5 because in R^3 the regular convex polytopes are the 5 Platonic solids.
		

References

  • H. S. M. Coxeter, Regular Polytopes, 3rd ed., Dover, NY, 1973.
  • B. Grünbaum, Convex Polytopes. Wiley, NY, 1967, p. 424.
  • P. McMullen and E. Schulte, Abstract Regular Polytopes, Encyclopedia of Mathematics and its Applications, Vol. 92, Cambridge University Press, Cambridge, 2002.

Crossrefs

Programs

  • Mathematica
    PadRight[{1, 1, -1, 5, 6}, 100, 3] (* Paolo Xausa, Jan 29 2025 *)

Formula

a(n) = 3 for all n > 4. - Christian Schroeder, Nov 16 2015

A021103 Number of two-connected (or biconnected) planar graphs with n nodes.

Original entry on oeis.org

0, 0, 0, 1, 3, 9, 44, 294, 2893, 36496, 545808, 9029737, 159563559, 2952794985, 56589742050
Offset: 0

Views

Author

Keywords

Comments

For n < 3, conventions vary: Read & Wilson set a(2) = 0, but Gagarin et al. set a(2) = 1. - Andrey Zabolotskiy, Jun 07 2023

References

  • R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998. See p. 229.

Crossrefs

Row sums of A049336.
The labeled version is A096331.
Cf. A000944 (3-connected), A002218, A003094, A005470.

Extensions

a(12)-a(14) from Gilbert Labelle (labelle.gilbert(AT)uqam.ca), Jan 20 2009
Offset 0 from Michel Marcus, Jun 05 2023
a(2) changed back to 0 by Georg Grasegger and Andrey Zabolotskiy, Jun 07 2023

A049337 Triangle read by rows: T(n,k) is the number of 3-connected planar graphs (or polyhedra) with n >= 1 nodes and 0 <= k <= C(n,2) edges.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 8, 11, 8, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 11, 42, 74, 76, 38, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 74, 296, 633, 768, 558, 219, 50
Offset: 1

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Author

Keywords

Examples

			Triangle begins
  0;
  0,0;
  0,0,0,0;
  0,0,0,1,0,0,0;
  0,0,0,0,0,1,1,0,0,0;
  0,0,0,0,0,0,1,2,2,...;
  ...
From _Hugo Pfoertner_, Nov 24 2020: (Start)
Transposed table:
.
                              Nodes                        Sums
       4  5  6   7   8    9    10     11     12    13  14 |A002840
  Edges-+--+--+---+---+----+-----+------+------+-----+---+|-------
   6 | 1  .  .   .   .    .     .      .      .     .   . |      1
   7 | .  .  .   .   .    .     .      .      .     .   . |      0
   8 | .  1  .   .   .    .     .      .      .     .   . |      1
   9 | .  1  1   .   .    .     .      .      .     .   . |      2
  10 | .  .  2   .   .    .     .      .      .     .   . |      2
  11 | .  .  2   2   .    .     .      .      .     .   . |      4
  12 | .  .  2   8   2    .     .      .      .     .   . |     12
  13 | .  .  .  11  11    .     .      .      .     .   . |     22
  14 | .  .  .   8  42    8     .      .      .     .   . |     58
  15 | .  .  .   5  74   74     5      .      .     .   . |    158
  16 | .  .  .   .  76  296    76      .      .     .   . |    448
  17 | .  .  .   .  38  633   633     38      .     .   . |   1342
  18 | .  .  .   .  14  768  2635    768     14     .   . |   4199
  19 | .  .  .   .   .  538  6134   6134    558     .   . |  13384
  20 | .  .  .   .   .  219  8822  25626   8822   219   . |  43708
  21 | .  .  .   .   .   50  7916  64439  64439  7916  50 | 144810
  .. | .  .  .   .   .    .    ..     ..     ..    ..  .. |     ..
     ---+--+--+---+---+----+-----+------+-------+----+---+
  Sums 1  2  7  34 257 2606 32300 440564 6384634 .. A000944
(End)
		

Crossrefs

A049337, A058787, A212438 are all versions of the same triangle.
Cf. A058788.

Extensions

Missing zeros inserted by Sean A. Irvine, Jul 29 2021

A000943 Number of combinatorial types of simplicial n-dimensional polytopes with n+3 nodes.

Original entry on oeis.org

1, 2, 5, 8, 18, 29, 57, 96, 183, 318, 604, 1080, 2047, 3762, 7145, 13354, 25471, 48164, 92193, 175780, 337581, 647313, 1246849, 2400828, 4636375, 8956045, 17334785, 33570800, 65108045, 126355319, 245492226, 477284164, 928772631, 1808538336
Offset: 1

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Author

Keywords

References

  • B. Grünbaum, Convex Polytopes. Wiley, NY, 1967, p. 424.
  • 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

Programs

  • Maple
    with(numtheory); n := 50; for d from 2 to n do C(d) := 0; for h from 1 to d+3 do if (h mod 2 = 1) and (d+3 mod h = 0) then C(d) := C(d) + phi(h) * 2^((d+3)/h); fi; od; C(d) := 2^(floor(d/2)) - floor ((d+4)/2) + C(d)/(4*(d+3)); od: A000943 := n-> eval(C(n));
  • Mathematica
    a[ n_ ] := 2^Floor[ n/2 ]-Floor[ (n+4)/2 ]+(1/(4*(n+3)))*Plus@@Map[ EulerPhi[ # ]*2^((n+3)/#)&, Select[ Divisors[ n+3 ], OddQ ] ]

Extensions

n=12 term corrected (typo in reference), formula (due to Perles) and more terms from Lukas Finschi (finschi(AT)ifor.math.ethz.ch), Mar 06 2001
Showing 1-10 of 29 results. Next