208569domain: NAppears in sequencesLet S denote the palindromes in the language {0,1,2}*; a(n) = number of words of length n in the language SS.at n=16A007056G.f.: Sum_{k>=1} x^(2*k)/(1+x^(2*k)) * Product_{k>=1} (1+x^k)/(1-x^k).at n=32A305122