754405836811domain: NAppears in sequencesa(n) = A205497(2*n, n - 1). The central coefficients of the Eulerian zig-zag polynomials.at n=9A373754a(n) = A205497(n, floor((n - 1) / 2)). The middle coefficients of the Eulerian zig-zag polynomials.at n=18A373755