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A034743
a(n) = Sum_{d | n} mu(n/d) * Bell(d-1).
2
1, 0, 1, 4, 14, 50, 202, 872, 4138, 21132, 115974, 678514, 4213596, 27644234, 190899306, 1382957668, 10480142146, 82864865614, 682076806158, 5832742183906, 51724158235168, 474869816040776, 4506715738447322
OFFSET
1,4
COMMENTS
A kind of Dirichlet convolution of mu(n) with Bell numbers.
LINKS
MATHEMATICA
a[n_] := Sum[MoebiusMu[n/d]*BellB[d - 1], {d, Divisors[n]}];
Array[a, 23] (* Jean-François Alcover, Sep 08 2019 *)
PROG
(PARI)
bell(n) = sum(k=0, n, stirling(n, k, 2));
a(n) = sumdiv(n, d, moebius(n/d) * bell(d-1)); \\ Andrew Howroyd, Apr 03 2017
CROSSREFS
KEYWORD
nonn
EXTENSIONS
More precise definition from Andrew Howroyd, Apr 03 2017
STATUS
approved