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 1-2 of 2 results.

A287220 Number of single-crossing partitions on n nodes.

Original entry on oeis.org

0, 0, 1, 4, 10, 36, 85, 312, 737, 2760, 6604, 25176
Offset: 0

Views

Author

Benedict W. J. Irwin, May 22 2017

Keywords

Comments

The meandric numbers A005316 are the numbers of paths which cross themselves 0 times.
This sequence is the number of paths that must cross themselves exactly once.

Examples

			a(2) = 1, this is from the partition (2,1).
a(3) = 4, this is from the partitions (1,3,2),(2,1,3),(2,3,1),(3,1,2).

Links

Crossrefs

Cf. A005316, A287221.

A287222 Number of 3-time self-crossing partitions on n nodes.

Original entry on oeis.org

0, 0, 0, 0, 2, 16, 164, 944, 4386, 22240, 83066, 398132
Offset: 0

Views

Author

Benedict W. J. Irwin, May 22 2017

Keywords

Comments

The meandric numbers A005316 are the numbers of paths which cross themselves 0 times.
This sequence is the number of paths that must cross themselves exactly 3 times.

Examples

			a(4) = 2, this is from the partitions (2,4,1,3) and (3,4,1,2).

Links

Crossrefs

Cf. A005316, A287220, A287221.
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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