Number triangle T(n,k) = binomial(n,k)*binomial(2n,n-k).

Terms

a(0) =1a(1) =2a(2) =1a(3) =6a(4) =8a(5) =1a(6) =20a(7) =45a(8) =18a(9) =1a(10) =70a(11) =224a(12) =168a(13) =32a(14) =1a(15) =252a(16) =1050a(17) =1200a(18) =450a(19) =50a(20) =1a(21) =924a(22) =4752a(23) =7425a(24) =4400a(25) =990a(26) =72a(27) =1a(28) =3432a(29) =21021