>>4401039It's powers of the square root of two, which is approximately 1.4, generally starting at 1. So it's 1, 1.4, and then every other number is a doubling.
>>4401056From 11 onwards they're rounded down (technically 22 would be 23 if you were doing the calculation, but because it's double 11 it's not). I've wondered who first decided it would be done from that point and if there were any exceptions but not really looked into it. At those higher values the decimal doesn't really matter, especially given the inaccuracy of f/ stops in the real world.
