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 28 results. Next

A173422 Partials sums of A003094 (unlabeled connected planar simple graphs with n nodes).

Original entry on oeis.org

1, 2, 3, 5, 11, 31, 130, 776, 6750, 78635, 1131440, 18580739, 331953037
Offset: 0

Views

Author

Jonathan Vos Post, Feb 18 2010

Keywords

Comments

Partials sums of number of unlabeled connected planar simple graphs with n nodes. The subsequence of primes in these partial sums begins: 2, 3, 5, 11, 31.

Examples

			a(11) = 1 + 1 + 1 + 2 + 6 + 20 + 99 + 646 + 5974 + 71885 + 1052805 + 17449299.
		

Crossrefs

Cf. A003094, inverse Euler transform of A005470, A126201.

Programs

Formula

a(n) = Sum_{i=0..n} A003094(i).

Extensions

Edited and a(12) added by M. F. Hasler, Mar 20 2018

A049379 Erroneous version of A003094.

Original entry on oeis.org

1, 1, 1, 2, 6, 20, 99, 646, 5918
Offset: 0

Views

Author

Keywords

A005470 Number of unlabeled planar simple graphs with n nodes.

Original entry on oeis.org

1, 1, 2, 4, 11, 33, 142, 822, 6966, 79853, 1140916, 18681008, 333312451
Offset: 0

Views

Author

Keywords

Comments

Euler transform of A003094. - Christian G. Bower

Examples

			a(2) = 2 since o o and o-o are the two planar simple graphs on two nodes.
		

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • W. T. Trotter, ed., Planar Graphs, Vol. 9, DIMACS Series in Discrete Mathematics and Theoretical Computer Science, Amer. Math. Soc., 1993.
  • Turner, James; Kautz, William H. A survey of progress in graph theory in the Soviet Union. SIAM Rev. 12 1970 suppl. iv+68 pp. MR0268074 (42 #2973). See p. 19. - N. J. A. Sloane, Apr 08 2014
  • Vetukhnovskii, F. Ya. "Estimate of the Number of Planar Graphs." In Soviet Physics Doklady, vol. 7, pp. 7-9. 1962. - From N. J. A. Sloane, Apr 08 2014
  • R. J. Wilson, Introduction to Graph Theory. Academic Press, NY, 1972, p. 162.

Crossrefs

Cf. A003094 (connected planar graphs), A034889, A039735 (planar graphs by nodes and edges).
Cf. A126201.

Programs

  • Mathematica
    A003094 = Cases[Import["https://oeis.org/A003094/b003094.txt", "Table"], {, }][[All, 2]];
    (* EulerTransform is defined in A005195 *)
    EulerTransform[Rest @ A003094] (* Jean-François Alcover, Apr 25 2013, updated Mar 17 2020 *)

Extensions

n=8 term corrected and n=9..11 terms calculated by Brendan McKay
Terms a(0) - a(10) confirmed by David Applegate and N. J. A. Sloane, Mar 09 2007
a(12) added by Vaclav Kotesovec after A003094 (computed by Brendan McKay), Dec 06 2014

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

Views

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

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

A049334 Triangle read by rows: T(n, k) is the number of unlabeled connected planar simple graphs with n >= 1 nodes and 0<=k<=3*n-6 edges.

Original entry on oeis.org

1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 2, 2, 1, 1, 0, 0, 0, 0, 3, 5, 5, 4, 2, 1, 0, 0, 0, 0, 0, 6, 13, 19, 22, 19, 13, 5, 2, 0, 0, 0, 0, 0, 0, 11, 33, 67, 107, 130, 130, 96, 51, 16, 5, 0, 0, 0, 0, 0, 0, 0, 23, 89, 236, 486, 804, 1112, 1211, 1026, 626, 275, 72, 14, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Keywords

Comments

Planar graphs with n >= 3 nodes have at most 3*n-6 edges.

Examples

			n\k 0  1  2  3  4  5  6  7  8  9 10 11 12
--:-- -- -- -- -- -- -- -- -- -- -- -- --
1:  1
2:  0  1
3:  0  0  1  1
4:  0  0  0  2  2  1  1
5:  0  0  0  0  3  5  5  4  2  1
6:  0  0  0  0  0  6 13 19 22 19 13  5  2
		

Crossrefs

Row sums are A003094.
Column sums are A046091.

Programs

  • nauty
    geng -c $n $k:$k | planarg -q | countg -q # Georg Grasegger, Jul 11 2023

Formula

T(n, n-1) = A000055(n) and Sum_{k} T(n, k) = A003094(n) if n>=1. - Michael Somos, Aug 23 2015
log(1 + B(x, y)) = Sum{n>0} A(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 A039735. - Michael Somos, Aug 23 2015

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

Views

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

Views

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

Views

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

A378103 Triangle read by rows: T(n,k) is the number of n-node connected unsensed planar maps with an external face and k triangular internal faces, n >= 3, 1 <= k <= 2*n - 5.

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 1, 2, 1, 0, 0, 2, 4, 4, 5, 4, 0, 0, 2, 6, 10, 14, 14, 18, 16, 0, 0, 0, 7, 18, 35, 49, 63, 69, 88, 78, 0, 0, 0, 5, 28, 74, 131, 204, 274, 345, 396, 489, 457, 0, 0, 0, 0, 26, 126, 304, 574, 893, 1290, 1708, 2137, 2503, 3071, 2938, 0, 0, 0, 0, 13, 159, 582, 1396, 2613, 4274, 6270, 8709, 11433, 14227, 16905, 20667, 20118
Offset: 3

Views

Author

Ya-Ping Lu, Nov 16 2024

Keywords

Comments

The planar maps considered are without loops or isthmuses.
In other words, a(n) is the number of embeddings in the plane of connected bridgeless planar simple graphs with n vertices and k triangular internal faces.
The number of edges is n + k - 1.
The nonzero terms in row n range from k = floor(n/2) through 2*n-5 and, thus, the number of nonzero terms is 2n - floor(n/2) - 4 = A001651(n-2).

Examples

			Triangle begins:
n\k        1     2     3     4     5     6     7     8     9    10    11
----     ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----
3          1
4          0     1     1
5          0     1     1     2     1
6          0     0     2     4     4     5     4
7          0     0     2     6    10    14    14    18    16
8          0     0     0     7    18    35    49    63    69    88    78
		

Crossrefs

Row sums are A377785.
Cf. A001651, A002713, A003094, A169808, A378336 (sensed), A378340 (achiral).
The final 3 terms of each row are in A002713, A005500, A005501.

Programs

Formula

T(n, 2*n-5) = A002713(n-3).
T(n,k) = (A378336(n,k) + A378340(n,k))/2.

Extensions

a(39) onwards from Andrew Howroyd, Nov 25 2024
Showing 1-10 of 28 results. Next