Riordan array ((1-2x)/(1+2x),x/(1+2x)^2).

Terms

a(0) =1a(1) =-4a(2) =1a(3) =8a(4) =-8a(5) =1a(6) =-16a(7) =36a(8) =-12a(9) =1a(10) =32a(11) =-128a(12) =80a(13) =-16a(14) =1a(15) =-64a(16) =400a(17) =-400a(18) =140a(19) =-20a(20) =1a(21) =128a(22) =-1152a(23) =1680a(24) =-896a(25) =216a(26) =-24a(27) =1a(28) =-256a(29) =3136