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A287253
Number of set partitions of [n] such that all absolute differences between least elements of consecutive blocks are <= three.
4
1, 1, 2, 5, 15, 51, 191, 780, 3440, 16249, 81736, 435796, 2453100, 14529728, 90294625, 587256087, 3988153356, 28223370977, 207745253237, 1587804229045, 12581186077773, 103197641796678, 875085283793768, 7661468372063681, 69173450911547978, 643354845906697516
OFFSET
0,3
LINKS
FORMULA
a(n) = A287216(n,3).
a(n) = A000110(n) for n <= 4.
CROSSREFS
Column k=3 of A287216.
Cf. A000110.
Sequence in context: A275605 A193296 A304454 * A117426 A201168 A001681
KEYWORD
nonn
AUTHOR
Alois P. Heinz, May 22 2017
STATUS
approved