Erroneous version of A003433.

Terms

a(0) =1a(1) =2a(2) =4a(3) =16a(4) =44a(5) =160a(6) =576a(7) =4096a(8) =14336a(9) =73728a(10) =327680a(11) =2985984a(12) =14929920a(13) =77635584