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 A051754 #25 Feb 11 2024 02:36:21 %S A051754 2,2,4,4,8,8,10,12,12,14,16,16,18,20,20,22,24,24,26,28,28,30,32,32,34, %T A051754 36,36,38,40,40,42,44,44,46,48,48,50,52,52,54,56,56,58,60,60,62,64,64, %U A051754 66,68,68,70,72,72,74,76,76,78,80,80,82,84,84,86 %N A051754 Consider problem of placing N queens on an n X n board so that each queen attacks precisely 1 other. Sequence gives maximal number of queens. %C A051754 2*[2n/3] is an upper bound for a(n). - _Jud McCranie_, Aug 12 2001 %C A051754 This bound is achieved for n=2, 4 and 6-65. %C A051754 Conjecture: a(n) = 2*[2n/3] for n >= 6. - _Alexander D. Healy_, Feb 10 2024 %D A051754 Martin Gardner, The Last Recreations, Copernicus, NY, 1997, 274-283. %H A051754 Alexander D. Healy, <a href="/A051754/a051754_1.pdf">Examples of optimal placements for n <= 65</a> %Y A051754 Cf. A051755-A051759, A051567-A051571, A019654, A063724. %K A051754 nonn,nice,more %O A051754 2,1 %A A051754 Robert Trent (trentrd(AT)hotmail.com), Aug 23 2000 %E A051754 a(12)-a(65) from _Alexander D. Healy_, Feb 10 2024