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%I #11 Oct 30 2022 18:19:59
%S 1,2,4,6,8,12,48,60,72,96,128,240,432,480,720,1728,2016,6912,10368,
%T 14080,32768,142560,184320,196560,712800,1140480,1190400,1658880,
%U 1801800,3345408,3571200,5702400,6220800,8363520,10222080,10368000,14859936,29719872,50319360
%N Numbers k such that k = phi(sigma(phi(sigma(k)))).
%t Select[Range[10^6], EulerPhi[DivisorSigma[1, EulerPhi[DivisorSigma[1, #]]]] == # &] (* _Amiram Eldar_, Apr 24 2022 *)
%Y Cf. A000010, A000203, A062401, A163372.
%K easy,nonn
%O 1,2
%A _Benoit Cloitre_, Mar 02 2002
%E More terms from _Reiner Martin_, Jul 09 2002
%E a(35)-a(39) from _Amiram Eldar_, Apr 24 2022
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