a(n) = gcd(Catalan(n), n!).

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =2a(5) =6a(6) =12a(7) =3a(8) =10a(9) =2a(10) =4a(11) =14a(12) =28a(13) =100a(14) =360a(15) =45a(16) =90a(17) =330a(18) =23100a(19) =2310a(20) =8580a(21) =780a(22) =1560a(23) =5850a(24) =468a(25) =1764a(26) =6664a(27) =476a(28) =52360a(29) =198968