75304domain: NAppears in sequencesTheta series of P_{11a} packing.at n=6A005953a(n) = [x^n] ( 1 + x*A(x)^n )^(n+1) / (n+1) for n>=0, with a(0)=1.at n=6A242794Number of n-step self-avoiding walks on a square lattice where no step can be in the same direction as the previous step.at n=21A337353