Triangle read by rows: T(n,k) is number of hex trees with n edges and k branches (1 <= k <= n).

Terms

a(0) =3a(1) =9a(2) =1a(3) =27a(4) =6a(5) =3a(6) =81a(7) =27a(8) =27a(9) =2a(10) =243a(11) =108a(12) =162a(13) =24a(14) =6a(15) =729a(16) =405a(17) =810a(18) =180a(19) =90a(20) =5a(21) =2187a(22) =1458a(23) =3645a(24) =1080a(25) =810a(26) =90a(27) =15a(28) =6561a(29) =5103