<Formula><+V>(A^2*H1^3)/(6*(H2+H1)*(H4+H1))+(A^2*H3^3)/(6*(H2+H3)*(H4+H3))</+V><-V>(A^2/6)*(2*H2+2*H4-H1-H3)+(A^2*H1^3)/(6*(H2+H1)*(H4+H1))+(A^2*H3^3)/(6*(H2+H3)*(H4+H3))</-V></Formula>