OFFSET
1,3
LINKS
Soheir M. Khamis, Height counting of unlabeled interval and N-free posets, Discrete Math. 275 (2004), no. 1-3, 165-175.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Dec 13 2011
EXTENSIONS
Missing term a(12) inserted by Salah Uddin Mohammad, May 26 2020
STATUS
approved