# number the equation without section or chapter [duplicate]

$$\label{N} (Nu)(x,y)=\mu(x,y)+\frac{1}{\Gamma(r_1)\cdot\Gamma(r_2)}\displaystyle{\int_{1}^{x}}\displaystyle{\int_{1}^{y}} \left(\log\frac{x}{s} \right)^{r_1-1}\left(\log\frac{y}{s} \right)^{r_2-1}\frac{f(s,t,u(s,t))}{st}dtds$$