a(n) = A269795(n)/2.

Terms

a(0) =1a(1) =0a(2) =3a(3) =1a(4) =15a(5) =12a(6) =63a(7) =14a(8) =252a(9) =240a(10) =1023a(11) =495a(12) =4095a(13) =4032a(14) =16365a(15) =2032a(16) =65535a(17) =65268a(18) =262143a(19) =130815a(20) =1048509a(21) =1047552a(22) =4194303a(23) =1048050a(24) =16777200a(25) =16773120a(26) =67108608a(27) =33550335a(28) =268435455a(29) =268418820