Awesome analysis @rviscomi!
This made me curious about other single character anchors, so I tweaked your query a bit to only output anchor text where LENGTH(anchor)=1. It looks like the anchor #s go from 0, 2, 3, 1 and then 4, 5, 6, 7, 8, 9.
The tree map below summarizes this. The size of each box represents the number of anchors containing that text. The color of the box represents the number of distinct URLs, and 0-9 are clearly among the most frequent (as you said, it’s likely due to pagination). Most of remaining top single character anchors consist of symbols used in navigation links (x + » X -) and western alphanumeric characters - although there are many non-western characters that make up the lower ~11K single character anchors in the lower right…
