Value making a function of two variables continuous at the origin

Let $f:\mathbb R^2\to\mathbb R$ be defined by

$$f(x,y)=\begin{cases}\dfrac{\sin\left(2(x^2+y^2)\right)}{x^2+y^2}\,e^{3x\sin\left(\frac4y\right)}, & (x,y)\ne(0,0),\ \alpha, & (x,y)=(0,0),\end{cases}$$

where $\alpha$ is a real constant. If $f$ is continuous at $(0,0)$, then $\alpha$ is equal to