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 A053560 #9 May 03 2019 07:49:11
%S A053560 0,0,0,1,6,14,36,93,252,661,1782,4893,13608,37890,106142,298755,
%T A053560 844182,2391732,6797196,19371684,55348596,158491993,454795398,
%U A053560 1307534319,3765720066,10862647236,31381000560,90780846494,262951692390
%N A053560 Number of ternary Lyndon words of length n with trace 0 and subtrace 1 over GF(3).
%H A053560 F. Ruskey, <a href="http://combos.org/TSlyndonF3">Ternary Lyndon words with given trace and subtrace over GF(3)</a>
%F A053560 (1/n) Sum mu(d) M(n/d, 2, 2); d|n, d=1(3) + (1/n) Sum mu(d) M(n/d, 1, 1); d|n, d=2(3), where M(n, t, s) = Sum n!/(i!j!k!); i+j+k=n, j=t(3), k=s(3)
%e A053560 a(4) = 1 = |{ 1122 }|
%Y A053560 Cf. A053548, A053561, A053562, A053563, A053564.
%K A053560 nonn
%O A053560 1,5
%A A053560 _Frank Ruskey_, Jan 17 2000