A202180 Number of n-element unlabeled connected N-free posets.

1, 1, 3, 9, 31, 115, 474, 2097, 9967, 50315, 268442, 1505463, 8840306, 54169431

Offset: 1

Author

N. J. A. Sloane, Dec 13 2011

Keywords

• nonn
• more

Links

• Soheir M. Khamis, Height counting of unlabeled interval and N-free posets, Discrete Math. 275 (2004), no. 1-3, 165-175.

Crossrefs

Row sums of A202178 and A202179.

Cf. A003430, A007453, A053554.

Extensions

Missing term a(12) inserted by Salah Uddin Mohammad, May 26 2020