Riordan array (1, x(1-2x)).

Terms

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