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%I #16 Jan 18 2024 01:39:26
%S 12,41,172,176,192,313,385,972,1008,1201,2732,2752,2816,3072,6668,
%T 7321,14281,15552,16128,25616,29425,41761,43696,43712,44032,45056,
%U 49152,78732,78768,79056,81648,84240,97241,106688,123921,139921
%N Numbers k such that phi(k) + k is a fourth power.
%H Amiram Eldar, <a href="/A114072/b114072.txt">Table of n, a(n) for n = 1..500</a>
%e phi(41) + 41 = 81 = 3^4.
%t Select[Range[140000],IntegerQ[Surd[#+EulerPhi[#],4]]&] (* _Harvey P. Dale_, Sep 27 2020 *)
%o (PARI) isok(n) = ispower(eulerphi(n) + n, 4); \\ _Michel Marcus_, Jan 09 2014
%Y Cf. A000010, A121048, subsequence of A114073.
%K nonn
%O 1,1
%A _Giovanni Resta_, Feb 13 2006