T(2n-1,n) where T is the array in A054126.

Terms

a(0) =2a(1) =7a(2) =39a(3) =236a(4) =1479a(5) =9418a(6) =60492a(7) =390720a(8) =2534115a(9) =16489802a(10) =107594725a(11) =703681448a(12) =4611414244a(13) =30273029080a(14) =199045400424