a(n) = T(2n, n-2), T given by A026769.

Terms

a(0) =1a(1) =10a(2) =71a(3) =444a(4) =2616a(5) =14938a(6) =83821a(7) =465654a(8) =2572166a(9) =14164320a(10) =77886902a(11) =428113940a(12) =2353823912a(13) =12950837432a(14) =71326701751a(15) =393289209772