OFFSET
0,4
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.
LINKS
B. W. J. Irwin, On the number of k-crossing partitions
EXAMPLE
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).
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Benedict W. J. Irwin, May 22 2017
STATUS
approved