a(n) = (2n+1)^2*Catalan(n).

Terms

a(0) =1a(1) =9a(2) =50a(3) =245a(4) =1134a(5) =5082a(6) =22308a(7) =96525a(8) =413270a(9) =1755182a(10) =7407036a(11) =31097794a(12) =130007500a(13) =541574100a(14) =2249204040a(15) =9316746045a(16) =38504502630a(17) =158814867750a(18) =653887380300