You get the lines because you're lining up all numbers divisible by 2, 3, 5 and 7. You get a very similar pattern with 210, and a sparser one with, for example, 30030.
Re:Prime Number Spiral
by christophilus on Sunday January 01, 2017 @08:23PM
(#13298470)
Yes, that's right. I wonder if it's a similar thing showing up in the spiral. Just a simple consequence like the one that causes the lines.
This never led me anywhere, for the record.