T(n,n+2), array T given by A047000.

Terms

a(0) =1a(1) =3a(2) =9a(3) =30a(4) =103a(5) =366a(6) =1323a(7) =4859a(8) =18033a(9) =67531a(10) =254620a(11) =965592a(12) =3679039a(13) =14074126a(14) =54023919a(15) =207985518a(16) =802774173a(17) =3105514305a(18) =12037590980a(19) =46743091795a(20) =181796906808a(21) =708073498446