%I #11 Dec 02 2020 07:22:15
%S 1,1,2,5,15,53,217,1013
%N a(n) = number of binary increasing trees with labels from {1,2,...n} which are beth-avoiding.
%C "beth" should be written as the Hebrew letter of that name.
%H Marilena Barnabei, Flavio Bonetti, Niccolò Castronuovo, Matteo Silimbani, <a href="https://doi.org/10.37236/9482">Permutations avoiding a simsun pattern</a>, The Electronic Journal of Combinatorics (2020) Vol. 27, Issue 3, P3.45.
%F See Barnabei et al. (2020), Th. 2, for a recurrence.
%K nonn,more
%O 0,3
%A _N. J. A. Sloane_, Dec 01 2020.