No-three-in-line $D(75)$
The largest number of points of the $75 \times 75$ grid with no three on a line.
Lower bound:
$148$
Verified
(not in the literature)
Upper bound:
$150$
Verified bounds
Verified bounds come with a certificate that is checked automatically: a formal proof in Lean, or an explicit construction checked by a program. Submit a certificate.
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Lower bound:
$148$
Checked construction
no-three-in-line-75-lower-148, submitted by daniel-munro, 2026-11-05 - Upper bound: None yet
Updates from the literature
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Upper bound: $150$
Trivial or easy according to the secondary source.
[via No-three-in-line problem - Wikipedia]