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

Terms

a(0) =1a(1) =1a(2) =3a(3) =8a(4) =22a(5) =62a(6) =184a(7) =566a(8) =1779a(9) =5678a(10) =18367a(11) =60091a(12) =198454a(13) =660659a(14) =2214700a(15) =7469730a(16) =25330135a(17) =86308528a(18) =295349232a(19) =1014609122a(20) =3497707471a(21) =12096300263a(22) =41955256710a(23) =145908382056a(24) =508676792788