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

Terms

a(0) =1a(1) =2a(2) =2a(3) =6a(4) =9a(5) =6a(6) =20a(7) =40a(8) =40a(9) =20a(10) =70a(11) =175a(12) =225a(13) =175a(14) =70a(15) =252a(16) =756a(17) =1176a(18) =1176a(19) =756a(20) =252a(21) =924a(22) =3234a(23) =5880a(24) =7056a(25) =5880a(26) =3234a(27) =924a(28) =3432a(29) =13728