No-three-in-line $D(24)$

48 points of the 24 by 24 grid with no three on a line

The largest number of points of the $24 \times 24$ grid with no three on a line.

Value: $48$ Verified lower bound

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.

Lower bound: $48$ Checked construction
no-three-in-line-24-lower-48, submitted by daniel-munro, 2026-11-05
[construction from The No-Three-in-Line Problem, Achim Flammenkamp, 2026-10-28]
Upper bound: None yet

Updates from the literature

Upper bound: $48$
Trivial or easy according to the secondary source.
[via No-three-in-line problem - Wikipedia]
1979-11 Lower bound: $48$
D.B. Anderson, Update on the no-three-in-line problem, Journal of Combinatorial Theory, Series A 27 (1979) 365-366.
[via The No-Three-in-Line Problem, Achim Flammenkamp, 2026-10-28]