128868696064domain: NAppears in sequencesa(n+2) = 2*a(n+1) + 2*a(n); a(0) = -1, a(1) = 1.at n=28A028860Expansion of g.f. (1-2*x^2)/(1-2*x-2*x^2).at n=26A152035Expansion of 2*x^2 / (1-2*x-2*x^2).at n=27A293007