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A322880
Number of set partitions of [n] such that the maximal absolute difference between the least elements of consecutive blocks equals seven.
2
0, 1, 67, 1059, 11373, 106256, 940608, 8193031, 71568443, 633413486, 5710573774, 52579554510, 494986212033, 4766754646529, 46966622143740, 473477764449909, 4883216510830794, 51513192445470426, 555667122424414886, 6127026713823497897, 69034256792655555566
OFFSET
7,3
LINKS
FORMULA
a(n) = A287257(n) - A287256(n).
MAPLE
b:= proc(n, k, m, l) option remember; `if`(n<1, 1,
`if`(l-n>k, 0, b(n-1, k, m+1, n))+m*b(n-1, k, m, l))
end:
A:= (n, k)-> b(n-1, min(k, n-1), 1, n):
a:= n-> (k-> A(n, k)-A(n, k-1))(7):
seq(a(n), n=7..30);
CROSSREFS
Column k=7 of A287215.
Sequence in context: A254640 A093267 A032651 * A157665 A231193 A078850
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Dec 29 2018
STATUS
approved