A276721 Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most five elements.

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

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Wikipedia, Partition of a set

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.

Cf. A276839, A276895.

Sequence in context: A343665 A192553 A053553 * A374329 A287583 A287276

Adjacent sequences: A276718 A276719 A276720 * A276722 A276723 A276724

Keyword

nonn,easy

Author

Alois P. Heinz, Sep 16 2016

Status

approved