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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

A kind of Dirichlet convolution of mu(n) with Bell numbers.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..100

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

Cf. A000110, A008683, A082951.

Sequence in context: A076024 A062807 A117421 * A096241 A283108 A211303

Adjacent sequences:  A034740 A034741 A034742 * A034744 A034745 A034746

KEYWORD

nonn

AUTHOR

Erich Friedman

EXTENSIONS

More precise definition from Andrew Howroyd, Apr 03 2017

STATUS

approved

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Last modified January 23 01:30 EST 2020. Contains 331166 sequences. (Running on oeis4.)