Triangle read by rows: T(n,k) = binomial(n+1,k+1) * binomial(4*n-3*k+1,k) / (n+1), 0<=k<=n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =6a(5) =1a(6) =1a(7) =15a(8) =21a(9) =1a(10) =1a(11) =28a(12) =110a(13) =56a(14) =1a(15) =1a(16) =45a(17) =350a(18) =550a(19) =126a(20) =1a(21) =1a(22) =66a(23) =855a(24) =2800a(25) =2145a(26) =252a(27) =1a(28) =1a(29) =91