Riordan array ((3-sqrt(1+8x))/2, (sqrt(1+8x)-1)/4).

Terms

a(0) =1a(1) =-2a(2) =1a(3) =4a(4) =-4a(5) =1a(6) =-16a(7) =16a(8) =-6a(9) =1a(10) =80a(11) =-80a(12) =32a(13) =-8a(14) =1a(15) =-448a(16) =448a(17) =-184a(18) =52a(19) =-10a(20) =1a(21) =2688a(22) =-2688a(23) =1120a(24) =-336a(25) =76a(26) =-12a(27) =1a(28) =-16896a(29) =16896