Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #10 May 08 2016 11:36:32
%S 1,2,3,5,6,9,22,33
%N Numbers n such that phi(Fibonacci(n)) is a square.
%C Corresponding distinct Fibonacci numbers for listed terms are 1, 2, 5, 8, 34, 17711, 3524578.
%C a(9) > 1000 (range of the b-file in A065449), if it exists. - _R. J. Mathar_, May 08 2016
%o (PARI) lista(nn) = for(n=1, nn, if(issquare(eulerphi(fibonacci(n))), print1(n, ", ")));
%Y Cf. A000010, A000045, A000290, A065449.
%K nonn,more
%O 1,2
%A _Altug Alkan_, May 06 2016