356895004domain: NAppears in sequencesa(0) = -1, a(1) = 2; a(n) = 2*a(n-1) + a(n-2).at n=23A078343Greedy frac multiples of sqrt(2): a(1)=1, Sum_{n>=0} frac(a(n)*x)=1 at x=sqrt(2).at n=33A079934Integers k such that 2*k^2 - 7 is a square.at n=22A217975a(n) = 6*a(n - 1) - a(n - 2) with a(0) = 2, a(1) = 8.at n=11A266507