3025308domain: NAppears in sequencesG.f. satisfies: A(x) = (1 + x*A(x)^2)^3.at n=7A212072a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/5)} a(5*k) * a(n-1-5*k).at n=37A386379Number of achiral polyominoes with n heptagonal cells of the hyperbolic regular tiling with Schläfli symbol {7,oo}.at n=15A389563