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 1-9 of 9 results.

A002851 Number of unlabeled trivalent (or cubic) connected simple graphs with 2n nodes.

Original entry on oeis.org

1, 0, 1, 2, 5, 19, 85, 509, 4060, 41301, 510489, 7319447, 117940535, 2094480864, 40497138011, 845480228069, 18941522184590, 453090162062723, 11523392072541432, 310467244165539782, 8832736318937756165
Offset: 0

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Examples

			G.f. = 1 + x^2 + 2*x^3 + 5*x^4 + 19*x^5 + 85*x^6 + 509*x^7 + 4060*x^8 + 41302*x^9 + 510489*x^10 + 7319447*x^11 + ...
a(0) = 1 because the null graph (with no vertices) is vacuously 3-regular.
a(1) = 0 because there are no simple connected cubic graphs with 2 nodes.
a(2) = 1 because the tetrahedron is the only cubic graph with 4 nodes.
a(3) = 2 because there are two simple cubic graphs with 6 nodes: the bipartite graph K_{3,3} and the triangular prism graph.
		

References

  • CRC Handbook of Combinatorial Designs, 1996, p. 647.
  • F. Harary, Graph Theory. Addison-Wesley, Reading, MA, 1969, p. 195.
  • R. C. Read, Some applications of computers in graph theory, in L. W. Beineke and R. J. Wilson, editors, Selected Topics in Graph Theory, Academic Press, NY, 1978, pp. 417-444.
  • R. C. Read and G. F. Royle, Chromatic roots of families of graphs, pp. 1009-1029 of Y. Alavi et al., eds., Graph Theory, Combinatorics and Applications. Wiley, NY, 2 vols., 1991.
  • R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
  • 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

Cf. A004109 (labeled connected cubic), A361407 (rooted connected cubic), A321305 (signed connected cubic), A000421 (connected cubic loopless multigraphs), A005967 (connected cubic multigraphs), A275744 (multisets).
Contribution (almost all) from Jason Kimberley, Feb 10 2011: (Start)
3-regular simple graphs: this sequence (connected), A165653 (disconnected), A005638 (not necessarily connected), A005964 (planar).
Connected regular graphs A005177 (any degree), A068934 (triangular array), specified degree k: this sequence (k=3), A006820 (k=4), A006821 (k=5), A006822 (k=6), A014377 (k=7), A014378 (k=8), A014381 (k=9), A014382 (k=10), A014384 (k=11).
Connected 3-regular simple graphs with girth at least g: A185131 (triangle); chosen g: this sequence (g=3), A014371 (g=4), A014372 (g=5), A014374 (g=6), A014375 (g=7), A014376 (g=8).
Connected 3-regular simple graphs with girth exactly g: A198303 (triangle); chosen g: A006923 (g=3), A006924 (g=4), A006925 (g=5), A006926 (g=6), A006927 (g=7). (End)

Extensions

More terms from Ronald C. Read

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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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

A072552 Number of connected planar regular graphs of degree 4 with n nodes.

Original entry on oeis.org

1, 0, 1, 1, 3, 3, 13, 21, 68, 166, 543, 1605, 5413, 17735, 61084, 210221, 736287
Offset: 6

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Author

Markus Meringer (meringer(AT)uni-bayreuth.de), Aug 05 2002

Keywords

Comments

Numbers were obtained using the graph generator GENREG in combination with a test for planarity implemented by M. Raitner.

Examples

			From _Allan Bickle_, May 13 2024: (Start)
For n=6, the unique graph is the octahedron.
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. A005964, A006820, A078666, A292515 (4-edge-connected graphs only).
Cf. A007022, A111361 (other 4-regular planar graphs).

Extensions

a(19)-a(22) from Andrey Zabolotskiy, Mar 21 2018 from Tuzun & Sikora.

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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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

A101204 Triangle read by rows: T(n,k) = number of planar trivalent (or cubic) loopless multigraphs with 2n nodes and exactly k double bonds, for 0 <= k <= n.

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 1, 1, 2, 1, 3, 4, 5, 4, 1, 9, 16, 22, 16, 7, 1, 32, 75, 112, 86, 41, 10, 1, 133
Offset: 0

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Author

N. J. A. Sloane, Dec 13 2004

Keywords

Comments

The entries in the first two rows are "by convention".

Examples

			Triangle begins
  1,
  0,  1,
  1,  0,   1,
  1,  1,   2,  1,
  3,  4,   5,  4,  1
  9, 16,  22, 16,  7,  1
 32, 75, 112, 86, 41, 10, 1
133, ...
		

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.

Crossrefs

Row sums give A005966. First column is A005964 (trivalent connected planar graphs with 2n nodes). Second and third columns give A101205, A101206.

A204186 Number of trivalent connected (or cubic) graphs with 2n nodes that are not planar.

Original entry on oeis.org

0, 0, 1, 2, 10, 53, 376, 3379, 37408, 485680, 7150241, 116726073, 2085446355
Offset: 1

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N. J. A. Sloane, Jan 12 2012

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Crossrefs

Equals A002851 - A005964.

A358284 Number of connected planar cubic graphs with 2*n nodes and zero edge-Kempe equivalence classes.

Original entry on oeis.org

0, 0, 0, 1, 3, 19, 98, 583, 3641, 24584, 174967
Offset: 2

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Author

N. J. A. Sloane, Nov 08 2022

Keywords

Comments

The reference gives further terms.

Crossrefs

Cf. A005964.

A358285 Number of connected planar cubic graphs with 2*n nodes and exactly one edge-Kempe equivalence class.

Original entry on oeis.org

1, 1, 1, 8, 28, 111, 556, 3108, 19368, 128811, 897475
Offset: 2

Views

Author

N. J. A. Sloane, Nov 08 2022

Keywords

Comments

The reference gives further terms.

Crossrefs

Cf. A005964.

A358286 Number of connected planar cubic graphs with 2*n nodes and the maximum number of edge-Kempe equivalence classes.

Original entry on oeis.org

1, 1, 1, 8, 1, 3, 27, 1, 1, 1, 7, 42, 1, 2
Offset: 2

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Author

N. J. A. Sloane, Nov 08 2022

Keywords

Crossrefs

Cf. A005964.
Showing 1-9 of 9 results.