Number triangle T(n,k) = C(n,n-k)*C(n+1,n-k).

Terms

a(0) =1a(1) =2a(2) =1a(3) =3a(4) =6a(5) =1a(6) =4a(7) =18a(8) =12a(9) =1a(10) =5a(11) =40a(12) =60a(13) =20a(14) =1a(15) =6a(16) =75a(17) =200a(18) =150a(19) =30a(20) =1a(21) =7a(22) =126a(23) =525a(24) =700a(25) =315a(26) =42a(27) =1a(28) =8a(29) =196