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 A054664 #19 Jul 02 2025 16:01:59
%S A054664 1,1,5,14,51,165,585,2032,7280,26163,95325,349350,1290555,4792905,
%T A054664 17895679,67106816,252645135,954429840,3616814565,13743869130,
%U A054664 52357696365,199911109725,764877654105,2932030657200,11258999068416
%N A054664 Number of 4-ary Lyndon words of length n with trace 0 mod 4.
%C A054664 Also number of 4-ary Lyndon words of length n with trace 2 mod 4.
%H A054664 F. Ruskey, <a href="http://combos.org/TSlyndon">Number of q-ary Lyndon words with given trace mod q</a>
%F A054664 From _Andrey Zabolotskiy_, Dec 19 2020: (Start)
%F A054664 a(n) = A068596(n) + A074403(n) + A074404(n) + A074405(n).
%F A054664 a(n) = A074410(n) + A074411(n) + A074412(n) + A074413(n). (End)
%t A054664 a[n_] := 1/(4 n) Sum[GCD[d, 4] MoebiusMu[d] 4^(n/d), {d, Divisors[n]}];
%t A054664 Array[a, 30] (* _Andrey Zabolotskiy_, Dec 19 2020 *)
%Y A054664 Cf. A000048, A051841, A046211, A046209, A054660, etc.
%K A054664 nonn,easy
%O A054664 1,3
%A A054664 _N. J. A. Sloane_, Apr 18 2000
%E A054664 More terms from _James Sellers_, Apr 19 2000