a(n) = A193737(2*n, n).

Terms

a(0) =1a(1) =2a(2) =8a(3) =36a(4) =170a(5) =826a(6) =4088a(7) =20496a(8) =103752a(9) =529100a(10) =2714140a(11) =13989560a(12) =72393412a(13) =375877684a(14) =1957199120a(15) =10216355632a(16) =53443289946a(17) =280101010170