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