Denominator of Sum_{k=0..n} 1/C(2*n,2*k).

Terms

a(0) =1a(1) =1a(2) =6a(3) =15a(4) =35a(5) =315a(6) =13860a(7) =3003a(8) =9009a(9) =765765a(10) =1385670a(11) =14549535a(12) =66927861a(13) =371821450a(14) =40156716600a(15) =145568097675a(16) =136745788725a(17) =128931743655