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A300129
Number of Motzkin trees that are "untypable closable skeletons".
0
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
Olivier Bodini, Paul Tarau, On Uniquely Closable and Uniquely Typable Skeletons of Lambda Terms, arXiv:1709.04302 [cs.PL], 2017.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Michael De Vlieger, Feb 25 2018
STATUS
approved