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 A161010 a(n) = Sum_{d|n} Moebius(n/d)*d^(b-1)/phi(n) for b = 14. 3
 1, 8191, 797161, 33550336, 305175781, 6529545751, 16148168401, 137422176256, 423644039001, 2499694822171, 3452271214393, 26745019396096, 25239592216021, 132269647372591, 243274230757741, 562881233944576, 619036127056621 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) is the number of lattices L in Z^13 such that the quotient group Z^13 / L is C_n. - Álvar Ibeas, Nov 26 2015 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 Álvar Ibeas, Table of n, a(n) for n = 1..10000 FORMULA a(n) = J_13(n)/J_1(n) where J_13 and J_1(n)=A000010(n) are Jordan functions. - R. J. Mathar, Jul 12 2011 From Álvar Ibeas, Nov 26 2015: (Start) Multiplicative with a(p^e) = p^(12e-12) * (p^13-1) / (p-1). For squarefree n, a(n) = A000203(n^12). (End) MAPLE f:= proc(n) local t; mul(t[1]^(12*t[2]-12)*(t[1]^13-1)/(t[1]-1), t = ifactors(n)[2]) end proc: seq(f(n), n=1..100); # Robert Israel, Dec 08 2015 MATHEMATICA b = 14; Table[Sum[MoebiusMu[n/d] d^(b - 1), {d, Divisors@ n}]/EulerPhi@ n, {n, 17}] (* Michael De Vlieger, Nov 27 2015 *) PROG (PARI) vector(100, n, sumdiv(n^12, d, if(ispower(d, 13), moebius(sqrtnint(d, 13))*sigma(n^12/d), 0))) \\ Altug Alkan, Nov 26 2015 CROSSREFS Cf. A160897. Sequence in context: A075960 A305758 A011563 * A075955 A075956 A022529 Adjacent sequences:  A161007 A161008 A161009 * A161011 A161012 A161013 KEYWORD nonn,mult AUTHOR N. J. A. Sloane, Nov 19 2009 EXTENSIONS Definition corrected by Enrique Pérez Herrero, Oct 30 2010 STATUS approved

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Last modified May 5 19:31 EDT 2021. Contains 343573 sequences. (Running on oeis4.)