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A202180 Number of n-element unlabeled connected N-free posets. 4
1, 1, 3, 9, 31, 115, 474, 2097, 9967, 50315, 268442, 1505463, 8840306, 54169431 (list; graph; refs; listen; history; text; internal format)
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
Row sums of A202178 and A202179.
Sequence in context: A225305 A365113 A110136 * A151034 A151035 A151036
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

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Last modified February 29 21:35 EST 2024. Contains 370428 sequences. (Running on oeis4.)