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

Terms

a(0) =1a(1) =-2a(2) =1a(3) =4a(4) =-3a(5) =1a(6) =-8a(7) =7a(8) =-4a(9) =1a(10) =16a(11) =-15a(12) =11a(13) =-5a(14) =1a(15) =-32a(16) =31a(17) =-26a(18) =16a(19) =-6a(20) =1a(21) =64a(22) =-63a(23) =57a(24) =-42a(25) =22a(26) =-7a(27) =1a(28) =-128a(29) =127