a(n) = (A001147(n) + A047974(n))/2.

Terms

a(0) =1a(1) =1a(2) =3a(3) =11a(4) =65a(5) =513a(6) =5363a(7) =68219a(8) =1016481a(9) =17243105a(10) =327431363a(11) =6874989963a(12) =158118876449