Triangular array, read by rows, associated with sums of certain Vandermonde determinants.

Terms

a(0) =1a(1) =2a(2) =1a(3) =3a(4) =4a(5) =1a(6) =4a(7) =10a(8) =8a(9) =1a(10) =5a(11) =20a(12) =35a(13) =16a(14) =1a(15) =6a(16) =35a(17) =112a(18) =126a(19) =32a(20) =1a(21) =7a(22) =56a(23) =294a(24) =672a(25) =462a(26) =64a(27) =1a(28) =8a(29) =84