A202180 - OEIS

%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