443156domain: NAppears in sequencesa(n) is the number of lattice paths from (0,0) to (2n,2n) using only the steps (1,0) and (0,1) and which do not touch any other points of the form (2k,2k).at n=6A337350Expansion of g.f. A(x) satisfying 1/x = Sum_{n=-oo..+oo} x^n * (x^(2*n) - (-1)^n*A(x))^(n+1).at n=16A361779