Riordan array ((1+3*x-sqrt(1+2*x+9*x^2))/(2*x),(1+3*x-sqrt(1+2*x+9*x^2))/2).

Terms

a(0) =1a(1) =-2a(2) =1a(3) =2a(4) =-4a(5) =1a(6) =2a(7) =8a(8) =-6a(9) =1a(10) =-10a(11) =-4a(12) =18a(13) =-8a(14) =1a(15) =6a(16) =-24a(17) =-26a(18) =32a(19) =-10a(20) =1a(21) =42a(22) =60a(23) =-18a(24) =-72a(25) =50a(26) =-12a(27) =1a(28) =-102a(29) =24