Numerator of Product_{2 <= p < 2*n} (2*n - p)/p.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =3a(6) =9a(7) =9a(8) =5a(9) =27a(10) =135a(11) =7a(12) =567a(13) =3375a(14) =45a(15) =54675a(16) =1215a(17) =25a(18) =13395375a(19) =168399a(20) =1625a(21) =4975425a(22) =164025a(23) =13125a(24) =5373459a(25) =1031443875a(26) =145775a(27) =2015047125a(28) =5367718125a(29) =931