2326095798domain: NAppears in sequencesa(n) = Sum_{d|n} (2^d*3^(n/d)).at n=18A038039a(n) = 3*2^n + 2*3^n.at n=19A094125E.g.f.: 2 - exp(2) + Sum_{n>=1} 2^n * exp(3*x^n) / n!.at n=19A258903