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 A053564 #9 May 03 2019 07:48:56
%S A053564 0,0,1,3,6,13,36,93,243,645,1782,4914,13608,37890,106288,299025,
%T A053564 844182,2391363,6797196,19371684,55345784,158486625,454795398,
%U A053564 1307541690,3765720066,10862647236,31381059609,90780960426,262951692390
%N A053564 Number of ternary Lyndon words of length n with trace 1 and subtrace 2 over GF(3). Same as the number of ternary Lyndon words of length n with trace 2 and subtrace 2 over GF(3).
%H A053564 F. Ruskey, <a href="http://combos.org/TSlyndonF3">Ternary Lyndon words with given trace and subtrace over GF(3)</a>
%F A053564 (1/n) Sum mu(d) M(n/d, 1, 2); d|n, d=1, 2(3) where M(n, t, s) = Sum n!/(i!j!k!); i+j+k=n, j=t(3), k=s(3).
%e A053564 a(4) = 3 = |{ 0112, 0121, 0211 }|
%Y A053564 Cf. A053548, A053560, A053561, A053562, A053563.
%K A053564 nonn
%O A053564 1,4
%A A053564 _Frank Ruskey_, Jan 17 2000