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 1-3 of 3 results.

A218462 Number of simple perfect matching graphs on 2n nodes.

Original entry on oeis.org

1, 6, 101, 10413, 11557799
Offset: 1

Views

Author

Eric W. Weisstein, Mar 26 2013

Keywords

Comments

Perfect matchings exist only for graphs with an even number of nodes.

Links

Crossrefs

Cf. A218463 (connected simple perfect matching graphs).
Cf. A287652 (disconnected simple perfect matching graphs).
Cf. A286951.

Formula

a(n) = A218463(n) + A287652(n). - Eric W. Weisstein, May 29 2017
a(n) = A286951(2*n, n). - Andrew Howroyd, Sep 05 2019

A287652 Number of simple disconnected perfect matching graphs on 2n nodes.

Original entry on oeis.org

0, 1, 6, 116, 10888
Offset: 1

Views

Author

Eric W. Weisstein, May 29 2017

Keywords

Links

Crossrefs

Cf. A218462 (simple not-necessarily connected perfect matching graphs).
Cf. A218463 (connected perfect matching graphs).

Formula

a(n) = A218462(n) - A218463(n).

A325304 Irregular triangle read by rows: T(n,k) is the number of simple connected graphs on n unlabeled nodes with matching number k, (0 <= k <= floor(n/2)).

Original entry on oeis.org

1, 1, 0, 1, 0, 2, 0, 1, 5, 0, 1, 20, 0, 1, 16, 95, 0, 1, 22, 830, 0, 1, 29, 790, 10297, 0, 1, 37, 1479, 259563, 0, 1, 46, 2625, 166988, 11546911
Offset: 0

Views

Author

Andrew Howroyd, Sep 05 2019

Keywords

Examples

			Triangle begins:
  1;
  1;
  0, 1;
  0, 2;
  0, 1,  5;
  0, 1, 20;
  0, 1, 16,   95;
  0, 1, 22,  830;
  0, 1, 29,  790,  10297;
  0, 1, 37, 1479, 259563;
  0, 1, 46, 2625, 166988, 11546911;
  ...

Links

Crossrefs

Columns k=2..3 are A243800, A243801.
Row sums are A001349.
Cf. A286951 (not necessarily connected).
Cf. A218463 (right diagonal, even terms).
Cf. A263341, A294490.

Formula

T(2*n, n) = A218463(n).
Showing 1-3 of 3 results.

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