T(2n+6,n), where T is the array in A055830.

Terms

a(0) =13a(1) =109a(2) =707a(3) =4184a(4) =23720a(5) =131389a(6) =717927a(7) =3889730a(8) =20959485a(9) =112529350a(10) =602684170a(11) =3222508015a(12) =17211197614a(13) =91855019053a(14) =489986311295