A272776 - 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