7447951domain: NAppears in sequencesExpansion of (1 + 2*x)/(1 + 3*x + 4*x^2).at n=24A087168Numbers k dividing u(k), where the Lucas sequence is defined u(i) = u(i-1) - 2*u(i-2) with initial conditions u(0)=0, u(1)=1.at n=18A228439a(n) = 3*a(n-1) - 4*a(n-2) with a(0) = a(1) = 1.at n=24A247560