-18457556052domain: ZAppears in sequencesExpansion of 1/(1 + 2*x - x^2).at n=27A077985Expansion of 2+(1-2*x)/(-1+2*x+x^2).at n=29A176981a(n) = -2*a(n-1) + a(n-2) for n > 2, with a(0) = a(1) = 1, a(2) = 0.at n=30A215936