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 A074724 #24 Jun 18 2022 14:18:22
%S A074724 3,3,9,3,3,9,3,3,27,3,3,9,3,3,9,3,3,27,3,3,9,3,3,9,3,3,81,3,3,9,3,3,9,
%T A074724 3,3,27,3,3,9,3,3,9,3,3,27,3,3,9,3,3,9,3,3,81,3,3,9,3,3,9,3,3,27,3,3,
%U A074724 9,3,3,9,3,3,27,3,3,9,3,3,9,3,3,243,3,3,9,3,3,9,3,3,27,3,3,9,3,3,9,3,3
%N A074724 Highest power of 3 dividing F(4n) where F(k) is the k-th Fibonacci number.
%C A074724 If m == 1, 2 or 3 (mod 4) then F(m) is not divisible by 3.
%H A074724 Amiram Eldar, <a href="/A074724/b074724.txt">Table of n, a(n) for n = 1..10000</a>
%F A074724 If k == 1 or 2 (mod 3) then a(3^m*k) = 3^(m+1) for m>=0.
%F A074724 a(n) = A038500(A033888(n)). - _Amiram Eldar_, May 13 2022
%F A074724 a(n) = 3^A051064(n) (conjectured). - _Michel Marcus_, May 17 2022
%F A074724 Conjecture: a(n) = (sigma(3*n) - sigma(n))/(sigma(3*n) - 3*sigma(n)), where sigma(n) = A000203(n). Equivalently, a(n) = A088838(n) - A074724(n). - _Peter Bala_, Jun 10 2022
%t A074724 Table[3^IntegerExponent[Fibonacci[4n],3],{n,100}] (* _Harvey P. Dale_, Jun 03 2012 *)
%o A074724 (PARI) a(n) = 3^valuation(fibonacci(4*n), 3); \\ _Michel Marcus_, May 13 2022
%Y A074724 Cf. A000045, A000203, A038500, A033888, A051064, A074724, A088838.
%K A074724 nonn
%O A074724 1,1
%A A074724 _Benoit Cloitre_, Sep 04 2002