Triangle read by rows. T(n, k) = (1/2) * C(n, k) * C(3*n - 1, n) for n > 0 and T(0, 0) = 1.

Terms

a(0) =1a(1) =1a(2) =1a(3) =5a(4) =10a(5) =5a(6) =28a(7) =84a(8) =84a(9) =28a(10) =165a(11) =660a(12) =990a(13) =660a(14) =165a(15) =1001a(16) =5005a(17) =10010a(18) =10010a(19) =5005a(20) =1001a(21) =6188a(22) =37128a(23) =92820a(24) =123760a(25) =92820a(26) =37128a(27) =6188a(28) =38760a(29) =271320