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 A194532 Jordan function ratio J_6(n)/J_2(n). 1
 1, 21, 91, 336, 651, 1911, 2451, 5376, 7371, 13671, 14763, 30576, 28731, 51471, 59241, 86016, 83811, 154791, 130683, 218736, 223041, 310023, 280371, 489216, 406875, 603351, 597051, 823536, 708123, 1244061, 924483, 1376256, 1343433, 1760031, 1595601, 2476656, 1875531, 2744343 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Multiplicative with a(p^e) = p^(4*(e-1))*(p^2+p+1)*(p^2-p+1), e>0. Dirichlet convolution of A000583 with the multiplicative function which starts 1, 5, 10, 0, 26, 50, 50, 0, 0, 130, 122, 0, 170, 250, 260, 0, 290,.. LINKS Robert Israel, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A069091(n)/A007434(n). Dirichlet generating function zeta(s-4)*product_{primes p} (1+p^(2-s)+p^(-s)). Sum_{k=1..n} a(k) ~ c * n^5 / 5, where c = Product_{primes p} (1 + 1/p^3 + 1/p^5) = 1.2196771388395597011492820972459808778277319864216893177353903924... - Vaclav Kotesovec, Dec 18 2019 MAPLE f:= proc(n) local t;      mul(t[1]^(4*(t[2]-1))*((t[1]^2+1)^2-t[1]^2), t=ifactors(n)[2]) end proc: map(f, [\$1..100]); # Robert Israel, Jun 14 2016 MATHEMATICA JordanTotient[n_, k_: 1] := DivisorSum[n, #^k MoebiusMu[n/#] &] /; (n > 0) && IntegerQ@ n; Table[JordanTotient[n, 6]/JordanTotient[n, 2], {n, 12}] (* Michael De Vlieger, Jun 14 2016, after Enrique Pérez Herrero at A065959 *) CROSSREFS Cf. A065959. Sequence in context: A225705 A259758 A203173 * A065827 A318036 A326164 Adjacent sequences:  A194529 A194530 A194531 * A194533 A194534 A194535 KEYWORD nonn,mult,easy AUTHOR R. J. Mathar, Aug 28 2011 STATUS approved

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Last modified August 7 22:19 EDT 2020. Contains 336279 sequences. (Running on oeis4.)