Triangle read by rows: T(n,m) = binomial(n + m - 1, 2*m) + binomial(2*n - m - 2, 2*(n - m - 1)).

Terms

a(0) =2a(1) =2a(2) =2a(3) =2a(4) =6a(5) =2a(6) =2a(7) =11a(8) =11a(9) =2a(10) =2a(11) =17a(12) =30a(13) =17a(14) =2a(15) =2a(16) =24a(17) =63a(18) =63a(19) =24a(20) =2a(21) =2a(22) =32a(23) =115a(24) =168a(25) =115a(26) =32a(27) =2a(28) =2a(29) =41