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 A260320 #27 Jun 19 2017 18:34:47 %S A260320 0,0,0,0,1,0,4,11,42,89,329,1765,9197,45647,284743,1846189,11975869, %T A260320 83259065,621001708,4878630533,39333230881,336375931369,3029241762900, %U A260320 28439270037332,275986675209470,2789712437580722 %N A260320 Number of asymmetric characteristic solutions to the n-queens problem. %C A260320 The problem of placing eight queens on a chessboard so that no one of them can take any other in a single move is a particular case of the more general problem: On a square array of n X n cells place n objects, one on each of n different cells, in such a way that no two of them lie on the same row, column, or diagonal. %C A260320 There are no ordinary solutions for n < 5, and there is just one complete set of ordinary solutions for n = 5: 13524, 52413, 24135, 35241, 53142, 14253, 42531, 31425 (generated by reflection and rotation). %C A260320 On the ordinary chessboard of 8 X 8 cells there are a total of 92 solutions, consisting of 11 sets of equivalent ordinary solutions and one set of equivalent symmetric solutions. There are no doubly symmetric solutions in this case. These sets may be generated in the ordinary case by 15863724, 16837425, 24683175, 2571384, 25741863, 26174835, 26831475, 27368514, 27581463, 35841726, 36258174 and in the symmetric case by 35281746. %D A260320 W. Ahrens, Mathematische Unterhaltungen und Spiele, second edition (1910), see page 231. %D A260320 Maurice Kraitchik: Mathematical Recreations. Mineola, NY: Dover, 2nd ed. 1953, pp. 247-255 (The Problem of the Queens). %H A260320 P. Capstick and K. McCann, <a href="/A000170/a000170_1.pdf">The problem of the n queens</a>, apparently unpublished, no date (circa 1990?) [Scanned copy] %H A260320 M. A. Sainte-Laguë, <a href="https://eudml.org/doc/192551">Les Réseaux (ou Graphes)</a>, Mémorial des Sciences Mathématiques, Fasc. 18, Gauthier-Villars, Paris, 1923, 64 pages. See p. 47. %H A260320 M. A. Sainte-Laguë, <a href="/A002560/a002560.pdf">Les Réseaux (ou Graphes)</a>, Mémorial des Sciences Mathématiques, Fasc. 18, Gauthier-Villars, Paris, 1923, 64 pages. See p. 47. [Incomplete annotated scan of title page and pages 18-51] %F A260320 a(n) = -A002562(n) + A000170(n)/4 + A260318(n)/2 (n>1). - _R. J. Mathar_, Jul 24 2015 %Y A260320 A002562 = A260318 + A260319 + A260320, A000170 = 2*A260318 + 4*A260319 + 8*A260320 (n>1). %K A260320 nonn,more %O A260320 1,7 %A A260320 _N. J. A. Sloane_, Jul 22 2015 %E A260320 Offset corrected by _Michael Somos_, Jun 19 2017