Row T(n,3) of number array A086404.

Terms

a(0) =1a(1) =4a(2) =18a(3) =84a(4) =396a(5) =1872a(6) =8856a(7) =41904a(8) =198288a(9) =938304a(10) =4440096a(11) =21010752a(12) =99423936a(13) =470479104a(14) =2226331008a(15) =10535111424a(16) =49852682496a(17) =235905426432