a(n) = A389805(2*n).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =5a(5) =19a(6) =89a(7) =489a(8) =3122a(9) =22777a(10) =189016a(11) =1761266a(12) =18557581a(13) =218008848