

A287222


Number of 3time selfcrossing partitions on n nodes.


0



0, 0, 0, 0, 2, 16, 164, 944, 4386, 22240, 83066, 398132
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OFFSET

0,5


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.


LINKS

Table of n, a(n) for n=0..11.
B. W. J. Irwin, On the number of kcrossing partitions


EXAMPLE

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


CROSSREFS

Cf. A005316, A287220, A287221.
Sequence in context: A226012 A011552 A326362 * A216598 A219397 A275912
Adjacent sequences: A287219 A287220 A287221 * A287223 A287224 A287225


KEYWORD

nonn,more


AUTHOR

Benedict W. J. Irwin, May 22 2017


STATUS

approved



