91893domain: NAppears in sequencesa(n) = Sum_{k=0..floor(n/2)} binomial(n,2*k)*J(k), where J = A001045.at n=15A101892G.f.: A(x) = ...o x/(1-x^4) o x/(1-x^3) o x/(1-x^2) o x/(1-x), composition of functions x/(1-x^n) for n = 1,2,3,...at n=12A136751