T(n,n-2), array T as in A047100.

Terms

a(0) =1a(1) =2a(2) =5a(3) =21a(4) =89a(5) =340a(6) =1312a(7) =5106a(8) =19782a(9) =76676a(10) =297776a(11) =1157609a(12) =4505193a(13) =17554888a(14) =68480902a(15) =267420957a(16) =1045329995a(17) =4089922224a(18) =16015961548a(19) =62768643959a(20) =246184737835a(21) =966243694608