A decomposition of the double factorials A001147.

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =2a(5) =0a(6) =1a(7) =10a(8) =4a(9) =0a(10) =1a(11) =36a(12) =60a(13) =8a(14) =0a(15) =1a(16) =116a(17) =516a(18) =296a(19) =16a(20) =0a(21) =1a(22) =358a(23) =3508a(24) =5168a(25) =1328a(26) =32a(27) =0a(28) =1a(29) =1086