Partial sums of (2n-1)!!.

Terms

a(0) =0a(1) =1a(2) =2a(3) =5a(4) =20a(5) =125a(6) =1070a(7) =11465a(8) =146600a(9) =2173625a(10) =36633050a(11) =691362125a(12) =14440672700a(13) =330674815925