a(n) = Sum_{k=0..n} 2^k * A000009(k) * A000041(n-k).

Terms

a(0) =1a(1) =3a(2) =8a(3) =27a(4) =67a(5) =189a(6) =509a(7) =1329a(8) =3344a(9) =8694a(10) =22062a(11) =54756a(12) =136741a(13) =335103a(14) =822277a(15) =2016738a(16) =4872787a(17) =11711655a(18) =28253743a(19) =67319328a(20) =160333627a(21) =381350646a(22) =901272326a(23) =2121969771a(24) =4991176893a(25) =11689645776a(26) =27305992220a(27) =63705989106a(28) =148106539514a(29) =343371565449