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A276721
Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most five elements.
6
1, 1, 2, 5, 15, 52, 151, 409, 1100, 3012, 8487, 23949, 67179, 187431, 521889, 1455667, 4066220, 11363476, 31747666, 88659265, 247559056, 691294366, 1930595096, 5391864630, 15058449487, 42054270461, 117445036871, 327989716409, 915985822220, 2558107420307
OFFSET
0,3
LINKS
FORMULA
G.f.: -(x^8 +x^6 +3*x^5 +2*x^3 +x^2 -1)/((x+1) *(x^15 +3*x^14 -x^13 +5*x^12 +15*x^11 +14*x^10 +9*x^9 +13*x^8 -17*x^7 -7*x^6 -21*x^5 -3*x^3 -2*x +1)).
CROSSREFS
Column k=5 of A276719.
Sequence in context: A343665 A192553 A053553 * A374329 A287583 A287276
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Sep 16 2016
STATUS
approved