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A272431
Number of ordered set partitions of {1,2,...,n} such that no part has the same size as any of its three immediate predecessors.
2
1, 1, 1, 7, 9, 31, 403, 757, 2873, 12607, 333051, 1592977, 10684875, 105031681, 697538325, 8987362027, 114294624633, 975751249951, 14157072527947, 124133073947209, 2048876740991939, 36859613739949357, 443133109281574185, 6166869485798451019
OFFSET
0,4
LINKS
CROSSREFS
Column k=3 of A261959.
Sequence in context: A272434 A272433 A272432 * A261961 A177030 A189974
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Apr 29 2016
STATUS
approved