290640domain: NAppears in sequencesNumber of n-step closed paths on hexagonal lattice.at n=9A002898E.g.f.: A(x) = Product_{n>=1} (1 + x^n/n)^n.at n=8A181541E.g.f. A(x) satisfies: Sum_{n>=0} x^n * exp(x*A(x)^n) / n! = exp(x*A(x) + x/A(x)).at n=7A340938