Triangle of certain double factorials.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =3a(5) =8a(6) =1a(7) =4a(8) =15a(9) =48a(10) =1a(11) =5a(12) =24a(13) =105a(14) =384a(15) =1a(16) =6a(17) =35a(18) =192a(19) =945a(20) =3840a(21) =1a(22) =7a(23) =48a(24) =315a(25) =1920a(26) =10395a(27) =46080a(28) =1a(29) =8