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Jan 19, 2023 at 6:25 history edited Jens Fischer CC BY-SA 4.0
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Jan 19, 2023 at 6:18 history edited Jens Fischer CC BY-SA 4.0
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Jan 19, 2023 at 6:12 history edited Jens Fischer CC BY-SA 4.0
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Jan 15, 2023 at 18:03 history edited Jens Fischer CC BY-SA 4.0
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Jan 15, 2023 at 11:50 history edited Jens Fischer CC BY-SA 4.0
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Jan 12, 2023 at 20:49 history edited Michael Hardy CC BY-SA 4.0
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Jan 12, 2023 at 19:45 comment added Jens Fischer Yes, this is equivalent to $\dfrac{n(n-1)}{2}$ being divisible by $3$ since there are exactly as many squares in the triangle.
Jan 12, 2023 at 15:30 comment added Peter Taylor With this modification the triples are always true triples so the number of uncovered squares is divisible by three unless $n \equiv 2 \pmod 3$. Revised solutions for n to 11.
Jan 12, 2023 at 14:39 history edited Jens Fischer CC BY-SA 4.0
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Jan 12, 2023 at 13:13 comment added Jens Fischer Sorry @PeterTaylor , I made a typo in the definition of (now) $\Gamma$. It was meant to be $m\leq n-(l-1)$ and not $m\leq n-l$. Also the third tuple then becomes $(k,n-(l-1))$. The tripple containing $(1,n-1)$ is then $(1,1),(1,2),(1,n-1)$.
Jan 12, 2023 at 13:06 history edited Jens Fischer CC BY-SA 4.0
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Jan 12, 2023 at 13:04 comment added The Amplitwist @WlodAA Related: Did mathcal stop working properly? on MathOverflow Meta.
Jan 12, 2023 at 12:45 history edited Jens Fischer CC BY-SA 4.0
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Jan 12, 2023 at 12:42 comment added Peter Taylor In fact, I think that leaving only 1 square uncovered is impossible for any even $n$, so either we're understanding the problem differently or your solution for $n=8$ must be wrong. Observe firstly that $(1, n-1)$ can never be covered; secondly that the number of $(i, 1)$ covered must be even; and thirdly that with $n$ even there are an odd number of $(i, 1)$.
Jan 12, 2023 at 11:59 comment added Peter Taylor Can you exhibit your solutions for 6, 7, 8? The ones I get using exhaustive search are worse, so I want to see whether it's a bug in my code or a misunderstanding of the problem.
Jan 12, 2023 at 11:11 comment added Jens Fischer Sure, I can change that
Jan 12, 2023 at 10:35 comment added Wlod AA Well, I got a small square symbol too just the same.
Jan 12, 2023 at 10:34 comment added Wlod AA Your mathcal symbols don't work on my screen, all of them show as small square symbols. Possibly, you could use "Delta" $\ \Delta,\ $ or "triangle" $\ \triangle,\ $ or nabla $\ \nabla,\ $ etc. ##### Let me try mathcal myself right here, $\ \mathcal T$ -- will it work properly?
Jan 12, 2023 at 9:55 history asked Jens Fischer CC BY-SA 4.0