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 A272776 #13 Aug 21 2025 18:50:16 %S A272776 1,2,3,5,6,9,22,33 %N A272776 Numbers k such that phi(Fibonacci(k)) is a square. %C A272776 Corresponding distinct Fibonacci numbers for listed terms are 1, 2, 5, 8, 34, 17711, 3524578. %C A272776 a(9) > 1000 (range of the b-file in A065449), if it exists. - _R. J. Mathar_, May 08 2016 %o A272776 (PARI) lista(nn) = for(n=1, nn, if(issquare(eulerphi(fibonacci(n))), print1(n, ", "))); %Y A272776 Cf. A000010, A000045, A000290, A065449. %K A272776 nonn,more %O A272776 1,2 %A A272776 _Altug Alkan_, May 06 2016