I’m not a big math nerd, but I’m also a programmer so maybe I have an slanted bias of what that means. Being ND also helps. I would love to see four consecutive numbers. I have kept two numbers around to now with 2 and 3 consecutive same digits. So XYY-ZYYY numbers without area code. With area code they are AYB-XYY-ZYYY for two diff area codes. I’d love giving up any Y overlap if the last four can be consecutive especially if it’s 4.