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A261483 Number of set partitions of [n] into exactly seven parts such that no part contains two elements with a circular distance less than three. 2
1, 12, 102, 720, 4587, 27326, 155571, 858023, 4623388, 24488768, 128053146, 663054996, 3407483161, 17409523182, 88545747922, 448749879028, 2267921345677, 11436557773522, 57571373075875, 289413549581585, 1453301573317896, 7291464343122268, 36557211011698580 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 7..1000

Index entries for linear recurrences with constant coefficients, signature (9,-25,70,-299,405,-746,2795,-19,3758,-7633,-12165,-17481,-9272,11804,14400,14400).

FORMULA

G.f.: -(120*x^9 +120*x^8 +71*x^7 +296*x^6 +86*x^5 +116*x^4 +32*x^3 +19*x^2 +3*x+1) *x^7 / ((x-1) *(5*x-1) *(3*x-1) *(2*x-1) *(4*x-1) *(x+1) *(x^2+x+1) *(5*x^2+x+1) *(3*x^2+x+1) *(4*x^2+x+1) *(2*x^2+x+1)).

EXAMPLE

a(7) = 1: 1|2|3|4|5|6|7.

a(8) = 12: 14|2|3|5|6|7|8, 15|2|3|4|6|7|8, 1|25|3|4|6|7|8, 16|2|3|4|5|7|8, 1|26|3|4|5|7|8, 1|2|36|4|5|7|8, 1|27|3|4|5|6|8, 1|2|37|4|5|6|8, 1|2|3|47|5|6|8, 1|2|38|4|5|6|7, 1|2|3|48|5|6|7, 1|2|3|4|58|6|7.

CROSSREFS

Column k=7 of A261477.

Sequence in context: A099299 A304504 A022736 * A082151 A125375 A217057

Adjacent sequences:  A261480 A261481 A261482 * A261484 A261485 A261486

KEYWORD

nonn,easy

AUTHOR

Alois P. Heinz, Aug 20 2015

STATUS

approved

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Last modified July 23 16:14 EDT 2019. Contains 325258 sequences. (Running on oeis4.)