Triangle read by rows T(n, k) = binomial(2*n, k) * binomial(3*n - k, 2*n).

Terms

a(0) =1a(1) =3a(2) =2a(3) =15a(4) =20a(5) =6a(6) =84a(7) =168a(8) =105a(9) =20a(10) =495a(11) =1320a(12) =1260a(13) =504a(14) =70a(15) =3003a(16) =10010a(17) =12870a(18) =7920a(19) =2310a(20) =252a(21) =18564a(22) =74256a(23) =120120a(24) =100100a(25) =45045a(26) =10296a(27) =924a(28) =116280a(29) =542640