#anchor-boxes

d2l generates anchor boxes centered on every pixel. With $n$ sizes $s_1, \ldots, s_n$ and $m$ aspect ratios $r_1, \ldots, r_m$ it keeps only the combinations that contain $s_1$ or $r_1$. How many anchor boxes does it generate for a $300 \times 400$ image with sizes=[0.75, 0.5, 0.25, 0.1] and ratios=[1, 2, 0.5]?