Numerator of n!!/(n+3)!!.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =8a(5) =5a(6) =16a(7) =7a(8) =128a(9) =21a(10) =256a(11) =33a(12) =1024a(13) =429a(14) =2048a(15) =715a(16) =32768a(17) =2431a(18) =65536a(19) =4199a(20) =262144a(21) =29393a(22) =524288a(23) =52003a(24) =4194304a(25) =185725a(26) =8388608a(27) =334305a(28) =33554432a(29) =9694845