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 A137279 #11 Nov 17 2015 16:27:26 %S A137279 1,4,0,16,40,192,560,3328,11772,63840,259336,1550976,7169656,42410256, %T A137279 234044160,1366190592 %N A137279 Number of ways of placing ceiling(n/2) nonattacking queens on an n X n Mobius chessboard. %C A137279 The chessboard is an n X n standard chessboard whose left and right edges are twisted connected. %H A137279 J. Bell and B. Stevens, <a href="http://ajc.maths.uq.edu.au/pdf/42/ajc_v42_p021.pdf">Results for the n-queens problem on the Mobius board</a>, Australasian Journal of Combinatorics, vol.42, p.21 (2008). %e A137279 a(4)=16 because any queen attacks all but two other squares and every solution is counted twice by enumerating all such placements. %Y A137279 Cf. A000170, A007705, A002562, A053994, A061989, A061990. %K A137279 nonn,more %O A137279 1,2 %A A137279 Brett Stevens (brett(AT)math.carleton.ca), Mar 13 2008