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%I #20 Jun 06 2022 05:48:17
%S 1,4,9,16,27,36,63,64,108,112,121,132,192,256,375,432,464,625,768,961,
%T 1024,1296,1309,1600,1620,2205,2304,2525,2597,3072,3136,3888,4096,
%U 4913,6561,8100,8500,8993,10064,10816,12352,13689,15376,16384,20480,25600,26000,28672
%N Numbers k such that Sum_{i=1..k} phi(i)/gcd(k,i) is an integer.
%H Amiram Eldar, <a href="/A066969/b066969.txt">Table of n, a(n) for n = 1..100</a>
%F If k = 4^j, j >= 0, k is in the sequence.
%t Select[Range[1000], IntegerQ[Sum[EulerPhi[i]/GCD[#, i], {i, 1, #}]] &] (* _Amiram Eldar_, Jun 06 2022 *)
%o (PARI) isok(n) = type(sum(i=1, n, eulerphi(i)/gcd(n,i))) == "t_INT"; \\ _Michel Marcus_, Nov 20 2013
%Y Cf. A066970.
%K nonn
%O 1,2
%A _Benoit Cloitre_, Jan 26 2002
%E More terms from _Michel Marcus_, Nov 20 2013
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