%I #14 Sep 21 2018 11:06:13
%S 91,18227,28605,137481,538849,2832797,3220333,384792005
%N Composite numbers k such that phi(k)^phi(k) == k + 1 (mod k^2).
%C Composite numbers k such that (k-phi(k))^phi(k) == 1 (mod k^2).
%o (PARI) isok(n) = n>1 && !isprime(n) && Mod(n-eulerphi(n), n^2)^eulerphi(n)==1;
%Y Cf. A003277, A077816.
%K nonn,more
%O 1,1
%A _Altug Alkan_, Sep 17 2018
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