Riordan array ((1+x)/(1-2x),x(1+x)/(1-2x)).

Terms

a(0) =1a(1) =3a(2) =1a(3) =6a(4) =6a(5) =1a(6) =12a(7) =21a(8) =9a(9) =1a(10) =24a(11) =60a(12) =45a(13) =12a(14) =1a(15) =48a(16) =156a(17) =171a(18) =78a(19) =15a(20) =1a(21) =96a(22) =384a(23) =558a(24) =372a(25) =120a(26) =18a(27) =1a(28) =192a(29) =912