This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A277433 #15 Feb 07 2025 09:43:50 %S A277433 1,4,4,4,6,6,8,8,8,8 %N A277433 Martin Gardner's minimal no-3-in-a-line problem, all slopes version. %C A277433 a(n) is the minimal number of counters that can be placed on an n X n grid, no three in a straight line, such that adding one more counter on any vacant grid point will produce three in a line. Lines can have any slope. %C A277433 The "queens" version of this problem, where lines are restricted to vertical, horizontal and diagonal, is A219760. %C A277433 a(11) <= 10, a(12) <= 10. %H A277433 Robert Israel, <a href="/A277433/a277433_1.pdf">Examples for n <= 12</a> (provably optimal for n <= 10). %H A277433 Sandi Klavžar, James Tuite, and Ullas Chandran, <a href="https://arxiv.org/abs/2501.19385">The General Position Problem: A Survey</a>, arXiv:2501.19385 [math.CO], 2025. See p. 39. %Y A277433 Cf. A219760. %K A277433 nonn,more %O A277433 1,2 %A A277433 _Robert Israel_, Oct 14 2016