This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A097647 #29 Jan 30 2025 16:52:05
%S A097647 190,427,429,724,924,4147,4697,6276,6726,7414,7964,9079,9709,10040,
%T A097647 10940,14450,15860,19190,20493,20553,28092,28215,29082,35502,39402,
%U A097647 41847,42777,44629,46899,49929,51282,51845,53075,54815,57035,57677
%N A097647 Non-palindromic numbers n such that phi(n) = phi(reversal(n)).
%C A097647 If n is in the sequence and 10 doesn't divide n then reversal(n) is also in the sequence. There exists three terms of this sequence less than 180000000 that reversal of them are primes,i.e. 10040,14450 and 1865170. This sequence has 445 composite terms less than 20000000 and there is no prime term up to 222000000. Has this sequence at least one prime term?
%C A097647 (190/99)*(100^m-1) is in the sequence iff 3 does not divide m (m is a term of A001651). So the sequence is infinite. A229903: 190, 19190, 191919190, 19191919190, ... are such terms. - _Jahangeer Kholdi_, Oct 17 2013
%C A097647 There are no prime terms < 10^10. - _Donovan Johnson_, Oct 18 2013
%e A097647 10040 is in the sequence because phi(10040)=phi(4001)=4000.
%t A097647 Do[If[n!=FromDigits[Reverse[IntegerDigits[n]]]&&EulerPhi[n]==EulerPhi[ FromDigits[Reverse[IntegerDigits[n]]]], Print[n]], {n, 80000}]
%Y A097647 Cf. A097648, A085329.
%Y A097647 Cf. A001651, A229903.
%K A097647 base,nonn
%O A097647 1,1
%A A097647 _Farideh Firoozbakht_, Aug 28 2004