%I A046209
%S A046209 1,1,2,6,16,38,104,270,726,1960,5368,14736,40880,113828,318848,896670,
%T A046209 2532160,7174050,20390552,58112088,166037248,475467916,1364393896,
%U A046209 3922624800,11297181456,32588003000,94143178098,272342710380
%N A046209 Number of ternary Lyndon words whose digits sum to 0 mod 3; also number 
               of trace 0 irreducible polynomials over GF(3).
%C A046209 Also number of ternary Lyndon words of trace 0 over GF(3).
%H A046209 <a href="Sindx_Lu.html#Lyndon">Index entries for sequences related to 
               Lyndon words</a>
%H A046209 F. Ruskey, <a href="http://www.theory.cs.uvic.ca/~cos/inf/neck/lyndon.html">
               Number of q-ary Lyndon words with given trace mod q</a>
%H A046209 F. Ruskey, <a href="http://www.theory.cs.uvic.ca/~cos/inf/neck/trace.html">
               Number of monic irreducible polynomials over GF(q) with zero trace 
               ...</a>
%H A046209 F. Ruskey, <a href="http://www.theory.csc.uvic.ca/~cos/inf/trs/lyn/Fq/
               lyn_tr_Fq.html">Number of Lyndon words of given trace</a>
%F A046209 ( Sum_{d|n} gcd(d, 3)*mu(d)*3^{n/d}) / (3n)
%e A046209 a(4)= 6 = |{ 0012, 0021, 0111, 0102, 0222, 1122 }|
%Y A046209 Cf. A046211.
%Y A046209 Sequence in context: A167821 A093041 A156616 this_sequence A078774 A129952 
               A057711
%Y A046209 Adjacent sequences: A046206 A046207 A046208 this_sequence A046210 A046211 
               A046212
%K A046209 nonn
%O A046209 1,3
%A A046209 Frank Ruskey (fruskey(AT)cs.uvic.ca), Dec 13 1999