Triangle read by rows: Polynomial coefficients per comment.

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =-2a(5) =3a(6) =1a(7) =-5a(8) =10a(9) =0a(10) =1a(11) =-9a(12) =31a(13) =-39a(14) =40a(15) =1a(16) =-14a(17) =77a(18) =-196a(19) =252a(20) =0a(21) =1a(22) =-20a(23) =162a(24) =-664a(25) =1457a(26) =-1476a(27) =1260a(28) =1a(29) =-27