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A261481 Number of set partitions of [n] into exactly five parts such that no part contains two elements with a circular distance less than three. 2
1, 3, 14, 44, 138, 458, 1397, 4219, 12974, 39270, 118004, 355924, 1071425, 3217011, 9662070, 29016280, 87083486, 261322358, 784185253, 2352907211, 7059288006, 21179391714, 63541238088, 190628647440, 571896993217, 1715715461187, 5147189398142, 15441653075684 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 5..1000

Index entries for linear recurrences with constant coefficients, signature (2,1,12,-6,-18,-47,-32,17,36,36).

FORMULA

G.f.: -(6*x^5+6*x^4+x^3+7*x^2+x+1)*x^5 / ((x-1) *(3*x-1) *(2*x-1) *(x+1) *(x^2+x+1) *(3*x^2+x+1) *(2*x^2+x+1)).

EXAMPLE

a(5) = 1: 1|2|3|4|5.

a(6) = 3: 14|2|3|5|6, 1|25|3|4|6, 1|2|36|4|5.

a(7) = 14: 14|25|3|6|7, 14|26|3|5|7, 14|2|36|5|7, 14|2|37|5|6, 15|26|3|4|7, 15|2|36|4|7, 15|2|37|4|6, 15|2|3|47|6, 1|25|36|4|7, 1|25|37|4|6, 1|25|3|47|6, 1|26|37|4|5, 1|26|3|47|5, 1|2|36|47|5.

CROSSREFS

Column k=5 of A261477.

Sequence in context: A305009 A115005 A058389 * A059672 A302225 A032316

Adjacent sequences:  A261478 A261479 A261480 * A261482 A261483 A261484

KEYWORD

nonn,easy

AUTHOR

Alois P. Heinz, Aug 20 2015

STATUS

approved

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Last modified June 25 10:28 EDT 2021. Contains 345453 sequences. (Running on oeis4.)