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%I #18 Jun 08 2020 05:24:19
%S 1,1,3,9,31,115,474,2097,9967,50315,268442,1505463,8840306,54169431
%N Number of n-element unlabeled connected N-free posets.
%H Soheir M. Khamis, <a href="https://doi.org/10.1016/S0012-365X(03)00106-7">Height counting of unlabeled interval and N-free posets</a>, Discrete Math. 275 (2004), no. 1-3, 165-175.
%Y Row sums of A202178 and A202179.
%Y Cf. A003430, A007453, A053554.
%K nonn,more
%O 1,3
%A _N. J. A. Sloane_, Dec 13 2011
%E Missing term a(12) inserted by _Salah Uddin Mohammad_, May 26 2020
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