[jll29]

A5 uses pentagons, Uber's H3 uses hexagons:

H3: Uber’s Hexagonal Hierarchical Spatial Index https://www.uber.com/en-DE/blog/h3/

[pheelicks]

Also check S2: http://s2geometry.io/, created at Google before H3, which uses squares and underpins the fast indexing in BigQuery amongst many other things