

A287582


Number of set partitions of [n] such that all absolute differences between least elements of consecutive blocks and between consecutive elements within the blocks are not larger than three.


2



1, 1, 2, 5, 15, 46, 139, 410, 1189, 3397, 9615, 27056, 75838, 212088, 592314, 1652806, 4609789, 12853354, 35832568, 99884249, 278414160, 776016655, 2162929636, 6028494326, 16802444328, 46831107603, 130525521011, 363794294041, 1013948759937, 2826024652739
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OFFSET

0,3


LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000
Wikipedia, Partition of a set
Index entries for linear recurrences with constant coefficients, signature (4,2,2,10,11,10,6,7,1,2)


FORMULA

G.f.: (2*x^9+7*x^86*x^6x^5+11*x^4+x^33*x+1) / ((x^2+x1) * (2*x^6 +3*x^5 6*x^3 3*x^2 x+1) * (x1)^2).
a(n) = A000110(n) for n <= 4.


CROSSREFS

Column k=3 of A287417.
Cf. A000110.
Sequence in context: A149913 A065848 A148359 * A122392 A139782 A047086
Adjacent sequences: A287579 A287580 A287581 * A287583 A287584 A287585


KEYWORD

nonn,easy


AUTHOR

Alois P. Heinz, May 26 2017


STATUS

approved



