176392domain: NAppears in sequencesa(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5, with initial values 1,-1,1,1.at n=27A025278Period of continued fraction for sqrt(k) equal for all a(n) <= k < a(n)+n.at n=6A031400Number of 2 X 2 matrices having all terms in {1,...,n} and determinant = 0 (mod 3).at n=25A210698