a(n) = coefficient of x^n in A(x) where 1 = Sum_{n=-oo..+oo} (x^n - x*A(x))^n.

Terms

a(0) =2a(1) =4a(2) =6a(3) =6a(4) =10a(5) =78a(6) =412a(7) =1394a(8) =3312a(9) =6416a(10) =17454a(11) =83334a(12) =384284a(13) =1377888a(14) =3931286a(15) =10234748a(16) =31776266a(17) =127848076a(18) =527518582a(19) =1910397078a(20) =6035143914a(21) =18202417974a(22) =60151348904a(23) =226355566282a(24) =874920531958