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%I #11 Mar 12 2020 07:27:47
%S 1,5,9,157,225,242,516,729,3872,13932,14406,17672,18225,20124,21780,
%T 29262,29616,45996,65025,76832,92778,95916,106092,106308,114630,
%U 114930,121872,125652,140130,140625,145794,149124,160986,179562,185100,234876
%N Numbers k such that sigma(phi(k)) == phi(sigma(k)) (mod k), that is, A033632(k)/k is an integer.
%H Amiram Eldar, <a href="/A092584/b092584.txt">Table of n, a(n) for n = 1..2000</a>
%e Includes but is not identical with A033632.
%e Below 10^7 only a(2) = 5 and a(4) = 157 give A033632(n)/n nonzero.
%t Select[Range[250000], Divisible[DivisorSigma[1, EulerPhi[#]] - EulerPhi[DivisorSigma[1, #]] , #] &] (* _Amiram Eldar_, Mar 12 2020 *)
%o (PARI) is(n)=sigma(eulerphi(n))==Mod(eulerphi(sigma(n)),n) \\ _Charles R Greathouse IV_, Nov 27 2013
%Y Cf. A033632, A092585, A092586, A092587, A092588, A065395.
%K nonn
%O 1,2
%A _Labos Elemer_, Mar 01 2004
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