Riordan matrix (1+x/sqrt(1-4*x),(1-sqrt(1-4*x))/2).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =1a(6) =6a(7) =5a(8) =3a(9) =1a(10) =20a(11) =15a(12) =9a(13) =4a(14) =1a(15) =70a(16) =49a(17) =29a(18) =14a(19) =5a(20) =1a(21) =252a(22) =168a(23) =98a(24) =49a(25) =20a(26) =6a(27) =1a(28) =924a(29) =594