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A178450 Dirichlet inverse of A034448 (unitary sigma). 1
1, -3, -4, 4, -6, 12, -8, -6, 6, 18, -12, -16, -14, 24, 24, 8, -18, -18, -20, -24, 32, 36, -24, 24, 10, 42, -12, -32, -30, -72, -32, -12, 48, 54, 48, 24, -38, 60, 56, 36, -42, -96, -44, -48, -36, 72, -48, -32, 14, -30, 72, -56, -54, 36, 72, 48, 80, 90, -60, 96, -62, 96, -48, 16, 84, -144, -68, -72, 96, -144 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..1000

FORMULA

Dirichlet g.f.: zeta(2s-1)/(zeta(s)*zeta(s-1)). - R. J. Mathar, Apr 14 2011

MATHEMATICA

usigma[n_] := If[n==1, 1, Times @@ (1 + Power @@@ FactorInteger[n])];

a[n_] := a[n] = If[n==1, 1, -Sum[usigma[n/d] a[d], {d, Most@Divisors[n]}]];

Array[a, 70] (* Jean-Fran├žois Alcover, Feb 16 2020 *)

PROG

(PARI) seq(n)={dirdiv(vector(n, n, n==1), vector(n, n, sumdivmult(n, d, if(gcd(d, n/d)==1, d))))} \\ Andrew Howroyd, Aug 05 2018

CROSSREFS

Cf. A034448.

Sequence in context: A008473 A326043 A069088 * A325973 A019462 A078071

Adjacent sequences:  A178447 A178448 A178449 * A178451 A178452 A178453

KEYWORD

sign,mult

AUTHOR

R. J. Mathar, Dec 22 2010

STATUS

approved

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Last modified September 19 03:31 EDT 2021. Contains 347550 sequences. (Running on oeis4.)