Riordan array ((1-x)/(1-3*x+3*x^2), x/(1-3*x+3*x^2)).

Terms

a(0) =1a(1) =2a(2) =1a(3) =3a(4) =5a(5) =1a(6) =3a(7) =15a(8) =8a(9) =1a(10) =0a(11) =33a(12) =36a(13) =11a(14) =1a(15) =-9a(16) =54a(17) =117a(18) =66a(19) =14a(20) =1a(21) =-27a(22) =54a(23) =297a(24) =282a(25) =105a(26) =17a(27) =1a(28) =-54a(29) =-27