T(n,n-2), array T given by A047010.

Terms

a(0) =1a(1) =2a(2) =3a(3) =15a(4) =61a(5) =248a(6) =990a(7) =3898a(8) =15296a(9) =59916a(10) =234410a(11) =916837a(12) =3586569a(13) =14035072a(14) =54948806a(15) =215250063a(16) =843689919a(17) =3308882412a(18) =12984859980a(19) =50985319491a(20) =200307492747a(21) =787380113112