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

Terms

a(0) =1a(1) =2a(2) =1a(3) =6a(4) =5a(5) =1a(6) =24a(7) =24a(8) =8a(9) =1a(10) =114a(11) =123a(12) =51a(13) =11a(14) =1a(15) =600a(16) =672a(17) =312a(18) =87a(19) =14a(20) =1a(21) =3372a(22) =3858a(23) =1914a(24) =618a(25) =132a(26) =17a(27) =1a(28) =19824a(29) =22992