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%I #12 Dec 11 2019 05:05:09
%S 1,3,2,6,4,3,9,2,8,6,7,4,5,12,7,3,4,10,9,7,2,5,8,6,5,14,4,10,7,5,7,5,
%T 12,10,4,3,9,14,3,10,8,10,11,15,4,9,4,2,9,3,5,6,4,7,2,8,5,15,4,11,4,5,
%U 10,16,7,10,6,13,9,2,6,7,5,4,4,6,2,8,2,15,5,8,4,11,10,12,8
%N Sequence gives values of sigma(n)^2 divided by UnitarySigma(n)*UnitaryPhi(n) associated with n in A121556.
%H Amiram Eldar, <a href="/A121647/b121647.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = f(A121556(n)), where f(m) = A000203(m)^2/(A034448(m)*A047994(m)). - _Amiram Eldar_, Dec 11 2019
%t f[p_, e_] := (p^(e+1)-1)^2/(p-1)^2/(p^(2*e)-1); ratio[1] = 1; ratio[n_] := Times @@ (f @@@ FactorInteger[n]); Select[ratio /@ Range[10^5], IntegerQ] (* _Amiram Eldar_, Dec 11 2019 *)
%Y Cf. A000203, A034448, A047994, A121556.
%K nonn
%O 1,2
%A _Yasutoshi Kohmoto_ Sep 12 2006
%E Extended with the aid of b121556.txt. - _R. J. Mathar_, Sep 04 2018
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