172789domain: NAppears in sequencesExpansion of Product_{k>=1} ((1 + x^(3*k)) / (1 - x^k))^k.at n=21A285447a(n) = n! * Sum_{k=0..floor(n/5)} (n/120)^k /(k! * (n-5*k)!).at n=11A362336