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 1-8 of 8 results.

A052437 Number of simple unlabeled n-node graphs with 1 center node.

Original entry on oeis.org

1, 0, 1, 2, 8, 29, 180, 1463, 20093, 474063, 20334351, 1602439752
Offset: 1

Views

Author

Keywords

Crossrefs

Column 1 of A294525 for n > 1.

Extensions

a(8)-a(10) from Andrew Howroyd, Nov 02 2017
a(11)-a(12) from Sean A. Irvine, Nov 23 2021

A052438 Number of simple unlabeled n-node graphs with 2 center nodes.

Original entry on oeis.org

0, 2, 0, 2, 4, 19, 84, 821, 12485, 343572, 16164685, 1289300669
Offset: 1

Views

Author

Keywords

Crossrefs

Column 2 of A294525 for n > 2.

Extensions

a(8)-a(10) from Andrew Howroyd, Nov 02 2017
a(11)-a(12) from Sean A. Irvine, Nov 23 2021

A052439 Number of simple unlabeled n-node graphs with 3 center nodes.

Original entry on oeis.org

0, 0, 3, 0, 4, 18, 119, 1055, 17297, 486446, 24269709, 2095669951
Offset: 1

Views

Author

Keywords

Crossrefs

Column 3 of A294525 for n > 3.

Extensions

a(8)-a(10) from Andrew Howroyd, Nov 02 2017
a(11)-a(12) from Sean A. Irvine, Nov 23 2021

A052440 Number of simple unlabeled n-node graphs with 4 center nodes.

Original entry on oeis.org

0, 0, 0, 7, 0, 18, 118, 1426, 24853, 763319, 39773455, 3569963990
Offset: 1

Views

Author

Keywords

Crossrefs

Column 4 of A294525 for n > 4.

Extensions

a(8)-a(10) from Andrew Howroyd, Nov 02 2017
a(11)-a(12) from Sean A. Irvine, Nov 23 2021

A052441 Number of simple unlabeled n-node graphs with 5 center nodes.

Original entry on oeis.org

0, 0, 0, 0, 18, 0, 129, 1390, 29987, 1015304, 59286916, 5764417079
Offset: 1

Views

Author

Keywords

Crossrefs

Column 5 of A294525 for n > 5.

Extensions

a(8)-a(10) from Andrew Howroyd, Nov 02 2017
a(11)-a(12) from Sean A. Irvine, Nov 23 2021

A324244 Triangle read by rows: T(n,k) is the number of simple connected graphs on n nodes with k peripheral nodes.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 2, 2, 0, 5, 4, 7, 5, 0, 25, 20, 16, 23, 28, 0, 185, 146, 119, 57, 123, 223, 0, 2459, 1728, 1523, 948, 405, 903, 3151, 0, 58156, 36109, 32119, 24637, 13927, 4713, 11746, 79673, 0, 2617378, 1446609, 1304109, 1026845, 723871, 353620, 110734, 279535, 3853870
Offset: 1

Views

Author

Andrew Howroyd, Sep 02 2019

Keywords

Comments

The peripheral nodes of a graph are those with eccentricity equal to the diameter.

Examples

			Triangle begins:
  1;
  0,     1;
  0,     1,     1;
  0,     2,     2,     2;
  0,     5,     4,     7,     5;
  0,    25,    20,    16,    23,    28;
  0,   185,   146,   119,    57,   123,  223;
  0,  2459,  1728,  1523,   948,   405,  903,  3151;
  0, 58156, 36109, 32119, 24637, 13927, 4713, 11746, 79673;
  ...
		

Crossrefs

Row sums give A001349.
Column k=2 is A324263.
Rightmost diagonal is A324264.

A324239 Irregular triangle read by rows: T(n,k) is the number of simple connected graphs on n nodes with radius k, (0 <= k <= floor(n/2)).

Original entry on oeis.org

1, 0, 1, 0, 2, 0, 4, 2, 0, 11, 10, 0, 34, 76, 2, 0, 156, 682, 15, 0, 1044, 9864, 207, 2, 0, 12346, 245518, 3197, 19, 0, 274668, 11366961, 74614, 326, 2
Offset: 1

Views

Author

Andrew Howroyd, Sep 02 2019

Keywords

Examples

			Triangle begins:
  1;
  0,      1;
  0,      2;
  0,      4,        2;
  0,     11,       10;
  0,     34,       76,     2;
  0,    156,      682,    15;
  0,   1044,     9864,   207,   2;
  0,  12346,   245518,  3197,  19;
  0, 274668, 11366961, 74614, 326, 2;
  ...
		

Crossrefs

Row sums give A001349.
Columns k=1..2 are A000088(n-1), A324061.

A324264 Number of simple connected graphs on n unlabeled nodes with diameter equal to radius.

Original entry on oeis.org

1, 1, 1, 2, 5, 28, 223, 3151, 79673, 3853870
Offset: 1

Views

Author

Andrew Howroyd, Sep 02 2019

Keywords

Comments

When the graph diameter is equal to the radius, every node has the same eccentricity and is in both the graph center and the graph periphery.

Crossrefs

Rightmost diagonal of A294525 and A324244.
Showing 1-8 of 8 results.