Triangle read by rows: g.f. (1 - t)^(-x) * (1 + t)^(2-x).

Terms

a(0) =1a(1) =2a(2) =1a(3) =1a(4) =0a(5) =4a(6) =0a(7) =3a(8) =1a(9) =0a(10) =6a(11) =6a(12) =0a(13) =5a(14) =6a(15) =1a(16) =0a(17) =16a(18) =24a(19) =8a(20) =0a(21) =14a(22) =23a(23) =10a(24) =1a(25) =0a(26) =60a(27) =110a(28) =60a(29) =10