Numerator of n!!/(n+1)!! (cf. A006882).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =8a(5) =5a(6) =16a(7) =35a(8) =128a(9) =63a(10) =256a(11) =231a(12) =1024a(13) =429a(14) =2048a(15) =6435a(16) =32768a(17) =12155a(18) =65536a(19) =46189a(20) =262144a(21) =88179a(22) =524288a(23) =676039a(24) =4194304a(25) =1300075a(26) =8388608a(27) =5014575a(28) =33554432a(29) =9694845