Second row of A113435.

Terms

a(0) =1a(1) =3a(2) =11a(3) =41a(4) =154a(5) =581a(6) =2197a(7) =8317a(8) =31501a(9) =119338a(10) =452141a(11) =1713111a(12) =6490879a(13) =24593701a(14) =93184802a(15) =353074657a(16) =1337790401a(17) =5068852073a(18) =19205744921a(19) =72770053106a(20) =275723780329