-18199284domain: ZAppears in sequencesA signed variant of the Motzkin numbers.at n=20A166587Expansion of (1+x+sqrt(1-2x-3x^2))/2.at n=21A168051Expansion of (1 - x + sqrt(1 - 2*x - 3*x^2))/2 in powers of x.at n=21A292440