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 A186966 #11 May 10 2021 00:45:41 %S A186966 0,24,296,1304,3808,8832,17672,31888,53312,84040,126440,183144,257056, %T A186966 351344,469448,615072,792192,1005048,1258152,1556280 %N A186966 Number of 3-turn queen's tours on an n X n board summed over all starting positions. %C A186966 Row 3 of A186965. %F A186966 Empirical: a(n) = 4*a(n-1)-5*a(n-2)+5*a(n-4)-4*a(n-5)+a(n-6). %F A186966 Empirical: a(n) = -6*n+1/4-30*n^3+73*n^2/3+67*n^4/6-(-1)^n/4 with g.f. -8*x^2*(3+25*x+30*x^2+9*x^3) / ( (1+x)*(x-1)^5 ), all terms multiples of 8. %e A186966 Some solutions for 3 X 3 %e A186966 ..2..0..3....3..0..0....2..3..0....3..0..0....0..3..0....0..0..1....3..1..0 %e A186966 ..0..0..0....0..2..0....0..0..0....1..2..0....0..0..2....0..0..0....0..2..0 %e A186966 ..1..0..0....0..0..1....1..0..0....0..0..0....0..0..1....2..0..3....0..0..0 %Y A186966 Cf. A186965. %K A186966 nonn %O A186966 1,2 %A A186966 _R. H. Hardin_ Mar 01 2011