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 A319096 #68 Dec 24 2018 08:56:12 %S A319096 1,14,459,35312,4072108,638653285,128441726634,31872148398195, %T A319096 9490641145219266,3321018871480028710 %N A319096 Number of nonequivalent ways to place n^2 nonattacking kings on a 2n X 2n chessboard under all symmetry operations of the square. %C A319096 A maximum of n^2 nonattacking kings may be placed on a 2n X 2n chessboard. %F A319096 a(n) = A236679(2n+1, n^2). %e A319096 For n = 2 there are a(2) = 14 distinct solutions from 79 that will not be repeated at all possible turns and reflections. %e A319096 ------------ %e A319096 1. 2. %e A319096 _________________ _________________ %e A319096 | * | | * | | | * | | * | | %e A319096 | | | | | | | | | | %e A319096 | * | | * | | | * | | | * | %e A319096 | | | | | | | | | | %e A319096 ------------ %e A319096 3. 4. %e A319096 _________________ _________________ %e A319096 | * | | * | | | * | | * | | %e A319096 | | | | | | | | | | %e A319096 | * | | | | | | * | | * | %e A319096 | | | | * | | | | | | %e A319096 ------------ %e A319096 5. 6. %e A319096 _________________ _________________ %e A319096 | * | | * | | | * | | * | | %e A319096 | | | | | | | | | | %e A319096 | | * | | | | | | * | | %e A319096 | | | | * | | * | | | | %e A319096 ------------ %e A319096 7. 8. %e A319096 _________________ _________________ %e A319096 | * | | * | | | * | | * | | %e A319096 | | | | | | | | | | %e A319096 | | | | * | | | | | | %e A319096 | * | | | | | * | | * | | %e A319096 ------------ %e A319096 9. 10. %e A319096 _________________ _________________ %e A319096 | * | | * | | | * | | * | | %e A319096 | | | | | | | | | | %e A319096 | | | | | | | | | * | %e A319096 | * | | | * | | | * | | | %e A319096 ------------ %e A319096 11. 12. %e A319096 _________________ _________________ %e A319096 | * | | * | | | * | | | * | %e A319096 | | | | | | | | | | %e A319096 | | | | | | | * | | | %e A319096 | | * | | * | | | | | * | %e A319096 ------------ %e A319096 13. 14. %e A319096 _________________ _________________ %e A319096 | * | | | * | | | * | | | %e A319096 | | | | | | | | | * | %e A319096 | | | | | | * | | | | %e A319096 | * | | | * | | | | * | | %e A319096 ------------ %Y A319096 Cf. A018807 (rotations and reflections considered distinct). %Y A319096 Cf. A137432 (on cylindrical chessboard). %Y A319096 Cf. A236679, A322284, A321614. %K A319096 nonn,more %O A319096 1,2 %A A319096 _Anton Nikonov_, Dec 21 2018 %E A319096 a(4)-a(10) from _Andrew Howroyd_, Dec 21 2018