Triangle of characteristic polynomials, see Mathematica code.

Terms

a(0) =1a(1) =1a(2) =-1a(3) =-2a(4) =-1a(5) =1a(6) =-6a(7) =3a(8) =3a(9) =-1a(10) =24a(11) =8a(12) =-13a(13) =-3a(14) =1a(15) =120a(16) =-40a(17) =-61a(18) =17a(19) =6a(20) =-1a(21) =-720a(22) =-180a(23) =360a(24) =75a(25) =-45a(26) =-6a(27) =1a(28) =-5040a(29) =1260