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 A189923 Jordan function J_{-5}(n) multiplied by n^5. 3
 1, -31, -242, -31, -3124, 7502, -16806, -31, -242, 96844, -161050, 7502, -371292, 520986, 756008, -31, -1419856, 7502, -2476098, 96844, 4067052, 4992550, -6436342, 7502, -3124, 11510052, -242, 520986, -20511148, -23436248 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For the Jordan function J_k see the Comtet and Apostol references. REFERENCES T. M. Apostol, Introduction to Analytic Number Theory, Springer, 1986. L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 199, #3. LINKS G. C. Greubel, Table of n, a(n) for n = 1..10000 (terms 1..200 from Indranil Ghosh) FORMULA a(n) = J_{-5}(n)*n^5 = Product_{p prime |n} (1-p^5), for n>=2, a(1)=1. a(n) = Sum_{d|n} mu(d)*d^5 with the Moebius function mu = A008683. Dirichlet g.f.: zeta(s)/zeta(s-5). Sum identity: Sum_{d|n} a(n)*(n/d)^5 = 1 for all n>=1. a(n) = a(rad(n)) with rad(n) = A007947(n), the squarefree kernel of n. G.f.: Sum_{k>=1} mu(k)*k^5*x^k/(1 - x^k). - Ilya Gutkovskiy, Jan 15 2017 EXAMPLE a(2) = a(4) = a(8) = ... = 1 - 2^5 = -31. a(4) = mu(1)*1^5 + mu(2)*2^5 + mu(4)*4^5 = 1 - 32 + 0 = -31. Sum identity for n=4: a(1)*(4/1)^5 + a(2)*(4/2)^5 + a(4)*(4/4)^5 = 1024 - 31*32 - 31 = 1. MATHEMATICA a[n_] := Sum[ MoebiusMu[d]*d^5, {d, Divisors[n]}]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Sep 03 2012 *) f[p_, e_] := (1-p^5); a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Dec 08 2020 *) PROG (PARI) for(n=1, 200, print1(sumdiv(n, d, moebius(d) * d^5), ", ")) \\ Indranil Ghosh, Mar 11 2017 (PARI) a(n) = sumdiv(n, d, moebius(d) * d^5); \\ Michel Marcus, Jan 14 2018 CROSSREFS Cf. A023900, A046970, A063453, A189922, for k=-1..-4. Sequence in context: A173832 A272162 A338893 * A059378 A024003 A258807 Adjacent sequences: A189920 A189921 A189922 * A189924 A189925 A189926 KEYWORD sign,easy,mult AUTHOR Wolfdieter Lang, Jun 16 2011 STATUS approved

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Last modified June 17 11:50 EDT 2024. Contains 373445 sequences. (Running on oeis4.)