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

Author

Michael De Vlieger, Feb 25 2018

Keywords

• nonn
• more

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

• 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.