81638domain: NAppears in sequencesE.g.f.: (exp(exp(x)-1)-1)^2.at n=8A052896D'Agapeyeff cipher.at n=8A135209D'Agapeyeff cipher.at n=18A135209Triangle read by rows: T(n,k) = ((Stirling2)^2)(n,k) * k!at n=29A233357