Triangle T(n,k) = k*binomial(n,k)*binomial(n-1,k) with T(n,0) = T(n,n) = 1, read by rows.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =1a(6) =1a(7) =6a(8) =6a(9) =1a(10) =1a(11) =12a(12) =36a(13) =12a(14) =1a(15) =1a(16) =20a(17) =120a(18) =120a(19) =20a(20) =1a(21) =1a(22) =30a(23) =300a(24) =600a(25) =300a(26) =30a(27) =1a(28) =1a(29) =42