The above is known to be the optimal 2D packing for equal-size circles. If you want to geek out, consider an algorithm for the optimal packing for unequal-size

The above is known to be the optimal 2D packing for equal-size circles. If you want to geek out, consider an algorithm for the optimal packing for unequal-size circles. Say, if there is an importance or frequency measure associated with each plotted circle. Now you've got yourself a math problem.