Triangle, read by rows, where the n-th row lists the (2*n+1) coefficients of (1 + x - 3*x^2)^n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =-3a(4) =1a(5) =2a(6) =-5a(7) =-6a(8) =9a(9) =1a(10) =3a(11) =-6a(12) =-17a(13) =18a(14) =27a(15) =-27a(16) =1a(17) =4a(18) =-6a(19) =-32a(20) =19a(21) =96a(22) =-54a(23) =-108a(24) =81a(25) =1a(26) =5a(27) =-5a(28) =-50a(29) =5