|
|
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
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
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
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|