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.

A218463 Number of simple connected perfect matching graphs on 2n nodes.

Original entry on oeis.org

1, 5, 95, 10297, 11546911
Offset: 1

Views

Author

Eric W. Weisstein, Mar 26 2013

Keywords

Comments

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

Crossrefs

Cf. A218462 (not-necessarily-connected simple perfect matching graphs).
Cf. A287652 (disconnected simple perfect matching graphs).

Formula

a(n) = A218462(n) - A287652(n). - Eric W. Weisstein, May 29 2017
Inverse Euler transform of A218462. - Andrew Howroyd, Nov 03 2017

A286951 Irregular triangle read by rows: T(n,k) is the number of simple graphs with n vertices with matching number k (0 <= k <= floor(n/2)).

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 4, 6, 1, 5, 28, 1, 6, 48, 101, 1, 7, 73, 963, 1, 8, 106, 1818, 10413, 1, 9, 147, 3383, 271128, 1, 10, 198, 6129, 441031, 11557799
Offset: 0

Views

Author

Eric W. Weisstein, May 17 2017

Keywords

Examples

			Triangle begins:
  1;
  1;
  1, 1;
  1, 3;
  1, 4,  6;
  1, 5,  28;
  1, 6,  48,  101;
  1, 7,  73,  963;
  1, 8, 106, 1818, 10413;
  ...
		

Crossrefs

Row sums are A000088.
T(2n,n) gives A218462 (for n>0).

Extensions

Name corrected by Andrew Howroyd, Nov 04 2017
T(0,0)=1 added by Alois P. Heinz, Nov 04 2017

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

Crossrefs

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

Formula

a(n) = A218462(n) - A218463(n).
Showing 1-3 of 3 results.