a(n) = lcm{1, ..., 2n} / binomial(2n, n).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =12a(5) =10a(6) =30a(7) =105a(8) =56a(9) =252a(10) =1260a(11) =330a(12) =1980a(13) =2574a(14) =2002a(15) =15015a(16) =240240a(17) =61880a(18) =15912a(19) =151164a(20) =38760a(21) =406980a(22) =4476780a(23) =1144066a(24) =13728792a(25) =24515700a(26) =6249100a(27) =84362850a(28) =21474180a(29) =5462730