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 A053561 #13 Aug 13 2024 04:12:55
%S A053561 0,1,2,3,6,15,36,87,234,645,1782,4893,13608,37994,106434,299025,
%T A053561 844182,2391723,6797196,19369708,55342972,158486625,454795398,
%U A053561 1307534319,3765720066,10862688116,31381118658,90780960426,262951692390
%N A053561 Number of ternary Lyndon words of length n with trace 0 and subtrace 2 over GF(3).
%H A053561 F. Ruskey, <a href="http://combos.org/TSlyndonF3">Ternary Lyndon words with given trace and subtrace over GF(3)</a>
%F A053561 (1/n) Sum mu(d) M(n/d, 1, 1); d divides n, d=1(3) + (1/n) Sum mu(d) M(n/d, 2, 2); d divides 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 A053561 a(4) = 3 = |{ 0012, 0021, 0102 }|
%Y A053561 Cf. A053548, A053560, A053562, A053563, A053564.
%K A053561 nonn
%O A053561 1,3
%A A053561 _Frank Ruskey_, Jan 17 2000