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A comment on An Interesting Pattern in the Prime Numbers: Parallax Compression. Parent comment

Re:An Interesting Pattern in the Prime Numbers: Parallax Com... by anderskaseorg on Friday May 18, 2018 @04:05PM (#17104563)
Can you explain how that picture would be produced with 75 numbers per square? The generalization that seems obvious to me already fails in both cells of row 2, because 75 is odd:

row 1, col 1: [1, 2, 3, …, 75], has primes

row 2, col 1: [76, 78, 80, …, 224], no primes

row 2, col 2: [77, 79, 81, …, 225], has primes

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Re:An Interesting Pattern in the Prime Numbers: Parallax Com... by tomsmeding on Friday May 18, 2018 @04:18PM (#17104639)
You are completely right; their pattern holds iff (I believe, not proven!) the number they take 75 for is even. If you take any even number of rows (== amount of numbers per cell, in their construction), say 6, or 74, or 76, the pattern works.
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Re:An Interesting Pattern in the Prime Numbers: Parallax Com... by anderskaseorg on Friday May 18, 2018 @04:20PM (#17104647)
No, it still fails for even n; see my other comment: https://news.ycombinator.com/item?id=17104624
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Re:An Interesting Pattern in the Prime Numbers: Parallax Com... by tomsmeding on Friday May 18, 2018 @04:23PM (#17104667)
Fair point, I missed that. Scratch my claim.

Then their claim that this pattern holds isn't even true; as pointed out elsewhere, and is obvious when you write out the sequence items explicitly in terms of their coordinates, any gcd!=1 cell will be red. But a gcd=1 cell need not be black, for many n.

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