Triangle, read by rows, T(n, k) = t(k, n-k+1) - t(1, n) + 1 where t(n, m) = (n*m)!*Beta(n, m).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =1a(6) =1a(7) =55a(8) =55a(9) =1a(10) =1a(11) =1993a(12) =12073a(13) =1993a(14) =1a(15) =1a(16) =120841a(17) =7983241a(18) =7983241a(19) =120841a(20) =1a(21) =1a(22) =11404081a(23) =12454040881a(24) =149448498481a(25) =12454040881a(26) =11404081a(27) =1a(28) =1a(29) =1556750161