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A220871 Number of partial matchings of n elements treatable by "PTR" (Procedure Triple Reverse). 0
1, 1, 2, 4, 10, 26, 76, 232, 756, 2548, 8906, 31846, 116422, 432758, 1634944 (list; graph; refs; listen; history; text; internal format)
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

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Last modified October 15 08:45 EDT 2018. Contains 316210 sequences. (Running on oeis4.)