Coefficient triangle of certain polynomials.

Terms

a(0) =1a(1) =1a(2) =-1a(3) =1a(4) =-2a(5) =-1a(6) =1a(7) =-4a(8) =-4a(9) =1a(10) =1a(11) =-7a(12) =-16a(13) =7a(14) =1a(15) =1a(16) =-12a(17) =-53a(18) =53a(19) =12a(20) =-1a(21) =1a(22) =-20a(23) =-166a(24) =318a(25) =166a(26) =-20a(27) =-1a(28) =1a(29) =-33