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A160892 ((2^b-1)/phi(n))*Sum_{d|n} Moebius(n/d)*d^(b-1) for b = 4. 0

%I

%S 15,105,195,420,465,1365,855,1680,1755,3255,1995,5460,2745,5985,6045,

%T 6720,4605,12285,5715,13020,11115,13965,8295,21840,11625,19215,15795,

%U 23940,13065,42315,14895,26880,25935,32235,26505,49140,21105,40005

%N ((2^b-1)/phi(n))*Sum_{d|n} Moebius(n/d)*d^(b-1) for b = 4.

%D 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.

%F a(n) = 15*A160889(n). - R. J. Mathar, Feb 07 2011

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Nov 19 2009

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Last modified May 27 05:24 EDT 2020. Contains 334649 sequences. (Running on oeis4.)