a(n)=a(n-1)^2*2^n-1 where a(0)=1.A073589a(n)=a(n-1)^2*2^n-1 where a(0)=1.Terms a(0) =1a(1) =1a(2) =3a(3) =71a(4) =80655a(5) =208167328799External referencesoeis: A073589