211901domain: NAppears in sequencesa(n) = n^4/2 - n^3 + 3*n^2/2 - n + 1 = (n^2 + 1)*(n^2 - 2*n + 2)/2.at n=26A058919Number of edges in a complete bipartite graph where the vertices in the two parts are placed on opposite sides of a parabola at integer x coordinates |x| = 1, 2, ...n.at n=26A392427