a(n) = T(2n-1,n-2), T given by A026769.

Terms

a(0) =1a(1) =8a(2) =49a(3) =276a(4) =1504a(5) =8082a(6) =43193a(7) =230536a(8) =1231484a(9) =6591350a(10) =35369380a(11) =190329098a(12) =1027180798a(13) =5559635866a(14) =30176648513a(15) =164237973028a(16) =896188159820