Riordan matrix (1/((1-x)*sqrt(1-4*x)),x/(1-x)).

Terms

a(0) =1a(1) =3a(2) =1a(3) =9a(4) =4a(5) =1a(6) =29a(7) =13a(8) =5a(9) =1a(10) =99a(11) =42a(12) =18a(13) =6a(14) =1a(15) =351a(16) =141a(17) =60a(18) =24a(19) =7a(20) =1a(21) =1275a(22) =492a(23) =201a(24) =84a(25) =31a(26) =8a(27) =1a(28) =4707a(29) =1767