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A276720 Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most four elements. 6
1, 1, 2, 5, 15, 37, 87, 208, 515, 1271, 3112, 7594, 18578, 45510, 111464, 272839, 667809, 1634784, 4002217, 9797781, 23985131, 58715973, 143739040, 351879841, 861416293, 2108779100, 5162371032, 12637686756, 30937555540, 75736343956, 185405513889, 453879917561 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
FORMULA
G.f.: -(x-1)*(x+1)/(x^8+3*x^7-5*x^5-5*x^4-x^3-2*x^2-x+1).
CROSSREFS
Column k=4 of A276719.
Sequence in context: A118387 A245961 A034522 * A148339 A148340 A148341
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Sep 16 2016
STATUS
approved

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Last modified February 25 13:12 EST 2024. Contains 370330 sequences. (Running on oeis4.)