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%I #19 Aug 06 2019 10:09:01
%S 1,21,63,291,2991,6102,46676013,69460293,2346534651,6313047393,
%T 23400000651,80050617822,234065340651,234659934651,2340000000651,
%U 2934000006591
%N Numbers n such that reverse(phi(n)) = n.
%C For all n, a(n) = reversal(A085331(n)), so see Comment on A085331. This sequence is a subsequence of A069215 and if m is a term of A069215 and 10 doesn't divide m then m is in this sequence. - _Farideh Firoozbakht_, Jan 09 2005
%C a(13) > 10^11. - _Donovan Johnson_, Feb 03 2012
%C a(17) > 10^13. - _Giovanni Resta_, Aug 06 2019
%e reverse(phi(6102)) = reverse(2016) = 6102, so 6102 is a term of the sequence.
%t Select[Range[10^5], FromDigits[Reverse[IntegerDigits[EulerPhi[#]]]] == # &] (* corrected by _Harvey P. Dale_, Oct 03 2011 *)
%Y Cf. A085331, A069215, A102278.
%K nonn,base,more
%O 1,2
%A _Joseph L. Pe_, Jul 21 2002
%E More terms from _Robert G. Wilson v_, Jul 23 2002
%E More terms from _Farideh Firoozbakht_, Jan 09 2005
%E a(10)-a(12) from _Donovan Johnson_, Feb 03 2012
%E a(13)-a(16) from _Giovanni Resta_, Aug 06 2019
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