80390domain: NAppears in sequencesNumber of ways to reciprocally link elements of an 5 X n array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links.at n=9A220710G.f. satisfies A(x) = 1 + x*A(x)^2 / (1 - x*A(x)^2)^3.at n=7A367240