Riordan array (1/u,(1-u)/2), u=sqrt(1-4x+4*x^3).

Terms

a(0) =1a(1) =2a(2) =1a(3) =6a(4) =3a(5) =1a(6) =18a(7) =9a(8) =4a(9) =1a(10) =58a(11) =29a(12) =13a(13) =5a(14) =1a(15) =192a(16) =96a(17) =44a(18) =18a(19) =6a(20) =1a(21) =650a(22) =325a(23) =151a(24) =64a(25) =24a(26) =7a(27) =1a(28) =2232a(29) =1116