T(2n,n-4), T given by A026758.

Terms

a(0) =1a(1) =14a(2) =125a(3) =911a(4) =5920a(5) =35785a(6) =205991a(7) =1145389a(8) =6208974a(9) =33019048a(10) =173020608a(11) =896198760a(12) =4599517316a(13) =23431544274a(14) =118650995097a(15) =597852859509