Riordan array (1,x(1-3x)).

Terms

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