O.g.f. A(x) satisfies: Sum_{n>=1} (x + (-1)^n*A(x))^n / n = 0.

Terms

a(0) =1a(1) =2a(2) =4a(3) =14a(4) =52a(5) =204a(6) =840a(7) =3574a(8) =15588a(9) =69332a(10) =313272a(11) =1433964a(12) =6635400a(13) =30988312a(14) =145871248a(15) =691403686a(16) =3296979524a(17) =15805913476a(18) =76135613784a(19) =368304184900