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.

A000944 Number of polyhedra (or 3-connected simple planar graphs) with n nodes.

Original entry on oeis.org

0, 0, 0, 1, 2, 7, 34, 257, 2606, 32300, 440564, 6384634, 96262938, 1496225352, 23833988129, 387591510244, 6415851530241, 107854282197058
Offset: 1

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Author

Keywords

References

  • H. T. Croft, K. J. Falconer and R. K. Guy, Unsolved Problems in Geometry, B15.
  • M. B. Dillencourt, Polyhedra of small orders and their Hamiltonian properties. Tech. Rep. 92-91, Info. and Comp. Sci. Dept., Univ. Calif. Irvine, 1992.
  • B. Grünbaum, Convex Polytopes. Wiley, NY, 1967, p. 424.
  • Y. Y. Prokhorov, ed., Mnogogrannik [Polyhedron], Mathematical Encyclopedia Dictionary, Soviet Encyclopedia, 1988.
  • 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).
  • G. M. Ziegler, Questions about polytopes, pp. 1195-1211 of Mathematics Unlimited - 2001 and Beyond, ed. B. Engquist and W. Schmid, Springer-Verlag, 2001.

Crossrefs

Extensions

More terms from Brendan McKay
a(18) from Brendan McKay, Jun 02 2006

A003094 Number of unlabeled connected planar simple graphs with n nodes.

Original entry on oeis.org

1, 1, 1, 2, 6, 20, 99, 646, 5974, 71885, 1052805, 17449299, 313372298, 5942258308
Offset: 0

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Author

Keywords

Comments

Inverse Euler transform of A005470. - Christian G. Bower, May 16 2003

Examples

			a(3) = 2 since the path o-o-o and the triangle are the two connected planar simple graphs on three nodes.
		

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • R. J. Wilson, Introduction to Graph Theory, Academic Press, NY, 1972, p. 162.

Crossrefs

Row sums of A049334.
The labeled version is A096332.

Programs

  • Mathematica
    a[n_Integer?NonNegative] := a[n] = Module[{m, s, g}, s = Subsets[Range[n], {2}]; m = Length[s]; g = Graph[Range[n], UndirectedEdge @@@ #] & /@ (Pick[s, #, 1] & /@ (IntegerDigits[#, 2, m] & /@ Range[0, 2^m - 1])); Length[DeleteDuplicates[Select[Select[g, ConnectedGraphQ], PlanarGraphQ], IsomorphicGraphQ]]]; Table[a[n], {n, 0, 6}] (* Robert P. P. McKone, Oct 14 2023 *)
  • nauty
    geng -c $n | planarg -q | countg -q # Georg Grasegger, Jul 06 2023

Extensions

More terms from Brendan McKay
a(12) added by Brendan McKay, Dec 06 2014
a(13) added by Georg Grasegger, Jul 06 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

A046091 Number of connected planar graphs with n edges.

Original entry on oeis.org

1, 1, 1, 3, 5, 12, 30, 79, 227, 709, 2318, 8049, 29372, 112000, 444855, 1833072, 7806724, 34252145, 154342391, 712231465, 3357126655, 16119421175, 78580665333
Offset: 0

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Author

Keywords

Comments

Inverse Euler transform of A343872. - Andrew Howroyd, May 05 2021

Examples

			a(3) = 3 since the three connected graphs with three edges are a path, a triangle and a "Y".
The first difference between this sequence and A002905 is for n=9 edges where we see K_{3,3}, the "utility graph".
		

Crossrefs

Row sums of A343873.
Column sums of A049334.

Programs

  • nauty
    # count graphs for the sequence by number of vertices v, sum over v afterwards
    geng -c $v $n:$n | planarg -q | countg -q # Georg Grasegger, Jul 06 2023

Extensions

a(11)-a(19) from Martin Fuller using nauty by Brendan McKay, Mar 07 2015
a(20)-a(22) added by Georg Grasegger, Jul 06 2023

A049336 Table read by rows: T(n,k) = number of 2-connected planar graphs with n >= 1 nodes and 0 <= k <= 3n-6 edges.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 2, 3, 2, 1, 0, 0, 0, 0, 0, 0, 1, 3, 9, 13, 11, 5, 2, 0, 0, 0, 0, 0, 0, 0, 1, 4, 20, 49, 77, 75, 47, 16, 5, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 40, 158, 406, 662, 737, 538, 259, 72, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 7, 70, 426, 1645, 4176, 7307, 8871, 7541, 4353, 1671, 378, 50
Offset: 1

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Author

Keywords

Examples

			Table begins:
  0;
  0, 0;
  0, 0, 0, 1;
  0, 0, 0, 0, 1, 1, 1;
  0, 0, 0, 0, 0, 1, 2, 3, 2,  1;
  0, 0, 0, 0, 0, 0, 1, 3, 9, 13, 11,  5,  2;
  0, 0, 0, 0, 0, 0, 0, 1, 4, 20, 49, 77, 75, 47, 16, 5;
  ...
		

Crossrefs

Extensions

More terms, a(86) onwards, from Gilbert Labelle (labelle.gilbert(AT)uqam.ca), Jan 20 2009

A039735 Triangle read by rows: T(n,k) = number of nonisomorphic unlabeled planar graphs with n >= 1 nodes and 0 <= k <= 3n-6 edges.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 2, 1, 1, 1, 1, 2, 4, 6, 6, 6, 4, 2, 1, 1, 1, 2, 5, 9, 15, 21, 24, 24, 20, 13, 5, 2, 1, 1, 2, 5, 10, 21, 41, 65, 97, 130, 144, 135, 98, 51, 16, 5, 1, 1, 2, 5, 11, 24, 56, 115, 221, 401, 658, 956, 1217, 1264, 1042, 631, 275, 72, 14, 1, 1, 2, 5
Offset: 1

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Author

Keywords

Comments

Planar graphs with n >= 3 nodes have at most 3n-6 edges. - Charles R Greathouse IV, Feb 18 2013

Examples

			Triangle starts
n\k 0  1  2  3  4  5  6  7  8  9 10 11 12
--:-- -- -- -- -- -- -- -- -- -- -- -- --
1:  1
2:  1  1
3:  1  1  1  1
4:  1  1  2  3  2  1  1
5:  1  1  2  4  6  6  6  4  2  1
6:  1  1  2  5  9 15 21 24 24 20 13  5  2
		

References

  • R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
  • R. J. Wilson, Introduction to Graph Theory. Academic Press, NY, 1972, p. 162.

Crossrefs

Cf. A005470 (row sums), A008406, A049334.

Formula

From Michael Somos, Aug 23 2015: (Start)
Sum_{k} T(n, k) = A005470(n) if n >= 1.
log(1 + A(x, y)) = Sum_{n>0} B(x^n, y^n) / n where A(x, y) = Sum_{n>0, k>=0} T(n,k) * x^n * y^k and similarly B(x, y) with A049334. (End)

A343870 Triangle read by rows: T(n,k) is the number of unlabeled nonseparable (or 2-connected) planar graphs with n edges and k nodes (n >= 1, 2 <= k <= n + 1).

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 3, 3, 1, 0, 0, 0, 0, 2, 9, 4, 1, 0, 0, 0, 0, 1, 13, 20, 6, 1, 0, 0, 0, 0, 0, 11, 49, 40, 7, 1, 0, 0, 0, 0, 0, 5, 77, 158, 70, 9, 1, 0, 0, 0, 0, 0, 2, 75, 406, 426, 121, 11, 1, 0, 0, 0, 0, 0, 0, 47, 662, 1645, 1018, 189, 13, 1, 0
Offset: 1

Views

Author

Andrew Howroyd, May 04 2021

Keywords

Examples

			Triangle T(n,k) begins (n edges >= 1, k vertices >= 2):
  1;
  0, 0;
  0, 1, 0;
  0, 0, 1, 0;
  0, 0, 1, 1,  0;
  0, 0, 1, 2,  1,  0;
  0, 0, 0, 3,  3,  1,   0;
  0, 0, 0, 2,  9,  4,   1,   0;
  0, 0, 0, 1, 13, 20,   6,   1,   0;
  0, 0, 0, 0, 11, 49,  40,   7,   1,  0;
  0, 0, 0, 0,  5, 77, 158,  70,   9,  1, 0;
  0, 0, 0, 0,  2, 75, 406, 426, 121, 11, 1, 0;
  ...
		

Crossrefs

Row sums are A343869.
Column sums are A021103.
Cf. A049334, A049336 (transpose), A049337, A253186, A339070.

Programs

  • nauty
    geng -C $k $n:$n | planarg -q | countg -q # Georg Grasegger, Jun 05 2023

Formula

T(n, n) = 1 for n >= 3.
T(n, n-1) = A253186(n-3) for n >= 3.

A343873 Triangle read by rows: T(n,k) is the number of unlabeled connected planar graphs with n edges and k nodes (n >= 0, 1 <= k <= n + 1).

Original entry on oeis.org

1, 0, 1, 0, 0, 1, 0, 0, 1, 2, 0, 0, 0, 2, 3, 0, 0, 0, 1, 5, 6, 0, 0, 0, 1, 5, 13, 11, 0, 0, 0, 0, 4, 19, 33, 23, 0, 0, 0, 0, 2, 22, 67, 89, 47, 0, 0, 0, 0, 1, 19, 107, 236, 240, 106, 0, 0, 0, 0, 0, 13, 130, 486, 797, 657, 235, 0, 0, 0, 0, 0, 5, 130, 804, 2075, 2678, 1806, 551
Offset: 0

Views

Author

Andrew Howroyd, May 06 2021

Keywords

Comments

First differs from A054923 in row n=9.
Terms may be computed using the tools geng and planarg in nauty.

Examples

			Triangle begins (n edges >= 0, k vertices >= 1):
  1;
  0, 1;
  0, 0, 1;
  0, 0, 1, 2;
  0, 0, 0, 2, 3;
  0, 0, 0, 1, 5,  6;
  0, 0, 0, 1, 5, 13,  11;
  0, 0, 0, 0, 4, 19,  33,  23;
  0, 0, 0, 0, 2, 22,  67,  89,  47;
  0, 0, 0, 0, 1, 19, 107, 236, 240, 106;
  0, 0, 0, 0, 0, 13, 130, 486, 797, 657, 235;
  ...
		

Crossrefs

Row sums are A046091.
Column sums are A003094.
Main diagonal is A000055.
Subsequent diagonals are A001429, A001435, A001436 (same as for not necessarily planar graphs).
Cf. A049334 (transpose), A054923, A343870.

Programs

  • nauty
    geng -c $k $n:$n | planarg -q | countg -q # Georg Grasegger, Jul 06 2023

A049340 Triangle read by rows: T(n,k) is the number of planar graphs with n >= 1 nodes and 0 <= k <= binomial(n,2) edges, all degrees even.

Original entry on oeis.org

1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 3, 2, 2, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 3, 4, 4, 6, 5, 5, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 3, 4, 7, 9, 15, 17, 22, 14, 16, 5, 4, 0, 1, 0, 0, 0
Offset: 1

Views

Author

Keywords

Examples

			Triangle begins:
  1;
  1, 0;
  1, 0, 0, 1;
  1, 0, 0, 1, 1, 0, 0;
  1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0;
  1, 0, 0, 1, 1, 1, 3, 2, 2, 1, 1, 0, 1, 0, 0, 0;
  ...
		

Crossrefs

Rows sums give A049339.

Extensions

Entry revised by Sean A. Irvine, Jul 29 2021
Showing 1-9 of 9 results.