A bisection of A222804.

Terms

a(0) =1a(1) =12a(2) =40a(3) =630a(4) =560a(5) =132a(6) =6006a(7) =156a(8) =19040a(9) =610470a(10) =41800a(11) =276a(12) =39468a(13) =12a(14) =15080a(15) =31150350a(16) =1180480a(17) =12a(18) =215333118a(19) =444a(20) =23993200a(21) =101072790a(22) =39560a(23) =564a(24) =63069864a(25) =132a(26) =2120a(27) =97064730a(28) =1477840a(29) =708