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A287222 Number of 3-time self-crossing partitions on n nodes. 0

%I

%S 0,0,0,0,2,16,164,944,4386,22240,83066,398132

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

%C The meandric numbers A005316 are the numbers of paths which cross themselves 0 times.

%C This sequence is the number of paths that must cross themselves exactly 3 times.

%H B. W. J. Irwin, <a href="https://www.authorea.com/users/5445/articles/173040-on-the-number-of-k-crossing-partitions/_show_article">On the number of k-crossing partitions</a>

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

%Y Cf. A005316, A287220, A287221.

%K nonn,more

%O 0,5

%A _Benedict W. J. Irwin_, May 22 2017

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Last modified May 25 20:58 EDT 2020. Contains 334597 sequences. (Running on oeis4.)