A300129 Number of Motzkin trees that are "untypable closable skeletons".

0, 0, 0, 1, 0, 2, 9, 10, 41, 128, 258, 821, 2360, 5813, 17185, 48721, 129678, 374519

Offset

0,6

Comments

From the Bodini-Tarau paper: a Motzkin skeleton is called "typable" if "it exists at least one simply-typed closed lambda term having it as its skeleton. An untypable skeleton is a closable skeleton for which no such term exists."

Links

Table of n, a(n) for n=0..17.

Olivier Bodini, Paul Tarau, On Uniquely Closable and Uniquely Typable Skeletons of Lambda Terms, arXiv:1709.04302 [cs.PL], 2017.

Crossrefs

Cf. A000108, A001006, A135501.

Sequence in context: A119183 A179888 A073082 * A191401 A363223 A338997

Adjacent sequences: A300126 A300127 A300128 * A300130 A300131 A300132

Keyword

nonn,more

Author

Michael De Vlieger, Feb 25 2018

Status

approved