39541748736domain: NAppears in sequencesDegree of variety K_{2,n}^4.at n=5A013701Expansion of g.f. (x^3 - 6*x^2 + 5*x - 1)/((2*x - 1)*(2*x^2 - 4*x + 1)).at n=22A024175Let M = {{0, -1, 2}, {-1, 2, -1}, {2, -1, 0}}; v[1] = {0, 0, 1}; v[n] = M.v[n - 1]; then a(n) = v[n][[1]].at n=21A124026