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A160891 Sum_{d|n} Moebius(n/d)*d^(b-1)/phi(n) for b = 5. 8
1, 15, 40, 120, 156, 600, 400, 960, 1080, 2340, 1464, 4800, 2380, 6000, 6240, 7680, 5220, 16200, 7240, 18720, 16000, 21960, 12720, 38400, 19500, 35700, 29160, 48000, 25260, 93600, 30784, 61440, 58560, 78300, 62400, 129600, 52060, 108600, 95200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

J. H. Kwak and J. Lee, Enumeration of graph coverings, surface branched coverings and related group theory, in Combinatorial and Computational Mathematics (Pohang, 2000), ed. S. Hong et al., World Scientific, Singapore 2001, pp. 97-161. See p. 134.

LINKS

Enrique Pérez Herrero, Table of n, a(n) for n = 1..5000

FORMULA

a(n)=J_4(n)/J_1(n)=J_4(n)/phi(n)=A059377(n)/A000010(n), where J_k is the k-th Jordan Totient Function [From Enrique Pérez Herrero, Oct 19 2010]

Multiplicative with a(p^e) = p^(3e-3)*(1+p+p^2+p^3). - R. J. Mathar, Jul 10 2011

MAPLE

A160891 := proc(n) a := 1 ; for f in ifactors(n)[2] do p := op(1, f) ; e := op(2, f) ; a := a*p^(3*e-3)*(1+p+p^2+p^3) ; end do; a; end proc:

seq(A160891(n), n=1..20) ; # R. J. Mathar, Jul 10 2011

MATHEMATICA

A160891[n_]:=DivisorSum[n, MoebiusMu[n/#]*#^(5-1)/EulerPhi[n]&] [From Enrique Pérez Herrero, Oct 19 2010]

CROSSREFS

Cf. A160893, A160895, A160897, A160960, A160972, A161010, A161025, A161139 , A161167, A161213, A065958, A065959, A065960 [From Enrique Pérez Herrero, Oct 19 2010]

Sequence in context: A044473 A067724 A005337 * A223425 A175926 A038991

Adjacent sequences:  A160888 A160889 A160890 * A160892 A160893 A160894

KEYWORD

nonn,mult

AUTHOR

N. J. A. Sloane, Nov 19 2009

EXTENSIONS

Definition corrected by Enrique Pérez Herrero, Aug 22 2010

STATUS

approved

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Last modified November 24 10:51 EST 2014. Contains 249895 sequences.