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Number of Motzkin trees that are "typable closed terms".
0

%I #7 Feb 27 2018 03:40:27

%S 0,1,2,3,10,34,98,339,1263,4626,18099,73782,306295,1319660,5844714,

%T 26481404,123172740

%N Number of Motzkin trees that are "typable closed terms".

%C 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".

%H Olivier Bodini, Paul Tarau, <a href="https://arxiv.org/abs/1709.04302">On Uniquely Closable and Uniquely Typable Skeletons of Lambda Terms</a>, arXiv:1709.04302 [cs.PL], 2017.

%Y Cf. A000108, A001006, A135501.

%K nonn,more

%O 0,3

%A _Michael De Vlieger_, Feb 25 2018