Erroneous version of A057835.

Terms

a(0) =4a(1) =24a(2) =144a(3) =908a(4) =6117a(5) =44159a(6) =332775a(7) =2592589a(8) =20758019a(9) =169922924a(10) =1416703346a(11) =11992874160a(12) =10283824252