Denominator of Sum_{k=0..n} 1/k!!.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =40a(6) =240a(7) =560a(8) =13440a(9) =120960a(10) =241920a(11) =887040a(12) =394240a(13) =138378240a(14) =276756480a(15) =593049600a(16) =66421555200a(17) =4136140800a(18) =173717913600