9313574419domain: NAppears in sequencesE.g.f. sqrt(D(x)^2 + S(x)^2), such that: C(x)^2 - S(x)^2 = 1 and D(x)^4 - S(x)^4 = 1, where functions S(x), C(x), and D(x) are described by A280625, A280626, and A280627, respectively.at n=7A280629