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%I #16 Sep 08 2022 08:45:23
%S 1,3,119,357,2522,6305,6596,6604,7566,18915,19788,19812,20520,24347,
%T 24353,26068,26082,28126,47959,58520,64790,65205,70315,73041,73059,
%U 73636,75460,78204,84378,143877,156519,164920,175560,194370,210945,212660,220908,226380
%N Numbers k such that phi(k)*sigma(k) is a cube.
%D J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 119, p. 41, Ellipses, Paris 2008.
%H Amiram Eldar, <a href="/A114077/b114077.txt">Table of n, a(n) for n = 1..6000</a>
%e phi(357) * sigma(357) = 110592 = 48^3.
%t Select[Range[10^5], IntegerQ @ Surd[EulerPhi[#] * DivisorSigma[1, #], 3] &] (* _Amiram Eldar_, Sep 19 2019 *)
%o (PARI) isok(n) = ispower(eulerphi(n)*sigma(n), 3); \\ _Michel Marcus_, Jan 22 2014
%o (Magma) [k:k in [1..230000]| IsPower(EulerPhi(k)*DivisorSigma(1,k),3)]; // _Marius A. Burtea_, Sep 19 2019
%Y Cf. A062354.
%K nonn
%O 1,2
%A _Giovanni Resta_, Feb 13 2006
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