A220871 Number of partial matchings of n elements treatable by "PTR" (Procedure Triple Reverse).

1, 1, 2, 4, 10, 26, 76, 232, 756, 2548, 8906, 31846, 116422, 432758, 1634944

Offset

1,3

Links

Table of n, a(n) for n=1..15.

Lily Yen, A Bijection for Crossings and Nestings, arXiv preprint arXiv:1209.3082, 2012

Crossrefs

Sequence in context: A239078 A303930 A007123 * A007578 A239079 A007580

Adjacent sequences: A220868 A220869 A220870 * A220872 A220873 A220874

Keyword

nonn

Author

N. J. A. Sloane, Dec 27 2012

Status

approved