a(n) = 2*a(n-1)*A002812(n-1), starting a(0)=1.A071579a(n) = 2*a(n-1)*A002812(n-1), starting a(0)=1.Terms a(0) =1a(1) =4a(2) =56a(3) =10864a(4) =408855776External referencesoeis: A071579