578524domain: NAppears in sequencesG.f. A(x) satisfies A(x) = 1 + x*A(x)*A(x^2)^2.at n=21A217925Number of non-equivalent (mod D_3) ways to choose three points in an n X n X n triangular grid so that they do not form a 2 X 2 X 2 subtriangle.at n=21A237530