294625domain: NAppears in sequencesa(n) = a(n-2)+a(n-3)+a(n-4)+a(n-5)+2*a(n-6)+a(n-7).at n=30A109541G.f. A(x) satisfies: A(x)^2 = A( x^2/(1-10*x) ), with A(0) = 0.at n=6A264227