12815663595domain: NAppears in sequencesNumber of binary Lyndon words containing n letters of each type; periodic binary sequences of period 2n with n zeros and n ones in each period.at n=21A022553Product_{n>=1} (1+x^n)^a(n) = Sum_{k>=0} C(k)*x^k, where C(k) = A000108(k).at n=20A378424