G.f. satisfies: A(x) = 1 + 2*x*AGM(1, A(x)^4).

Terms

a(0) =1a(1) =2a(2) =8a(3) =48a(4) =336a(5) =2560a(6) =20608a(7) =172432a(8) =1484704a(9) =13069296a(10) =117080576a(11) =1063944416a(12) =9783594304a(13) =90869069872a(14) =851218195008