While somewhat tangential to this, I'd like comment on a different problem. "What's the fewest number of plates you need to go from 45lb (bar) -> 240lb at a resolution of 5lb?" Look no further than the 185lb set[1]. Composed of pairs of 2.5lb, 5lb, 2x10lb, 25lb, 45lb plates, one can do just this. Need to lift 245lb? Buy another pair of 45lb plates and your range expands to 45lb -> 330lb. Another pair of 45lb plates yields 45lb -> 420lb. You get the idea. This approach comes with the added bonus of being the most cost efficient method of buying plates, as higher pound plates yield slightly better $/lb.

1: https://github.com/ramity/athena/blob/master/notebooks/plate...

Side note: I've yet to do the calculations for kg sets, but I'm certain something similar to this exists.

Edit: I made a laughably simple mistake interpreting my results and corrected the above. Many thanks to those who replied and brought this to my attention (credited in the commit https://github.com/ramity/athena/commit/4a17a3d16058f850d09e...).