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 A342997 #23 May 05 2021 13:58:52 %S A342997 1,0,5,27,0,4665,131106,0,204995269,11254190082 %N A342997 Maximum number of diagonal transversals in a cyclic diagonal Latin square of order 2n+1. %C A342997 A cyclic Latin square is a Latin square in which row i is obtained by cyclically shifting row i-1 by d places (see A338562, A123565 and A341585). %C A342997 Cyclic diagonal Latin squares do not exist for even n. %C A342997 All cyclic diagonal Latin squares are diagonal Latin squares, so a((n-1)/2) <= A287648(n). %C A342997 All diagonal transversals are transversals, so a(n) <= A006717(n). %C A342997 A342998 <= a(n). %H A342997 Eduard I. Vatutin, <a href="https://vk.com/wall162891802_1412">Enumerating the diagonal transversals for cyclic diagonal Latin squares of orders 1-19</a> (in Russian). %H A342997 Eduard I. Vatutin, <a href="/A342997/a342997.txt">Proving list (best known examples)</a>. %H A342997 <a href="/index/La#Latin">Index entries for sequences related to Latin squares and rectangles</a>. %e A342997 For n=2 one of the best cyclic diagonal Latin squares of order 5 %e A342997 0 1 2 3 4 %e A342997 2 3 4 0 1 %e A342997 4 0 1 2 3 %e A342997 1 2 3 4 0 %e A342997 3 4 0 1 2 %e A342997 has a(2)=5 diagonal transversals: %e A342997 0 . . . . . 1 . . . . . 2 . . . . . 3 . . . . . 4 %e A342997 . . 4 . . . . . 0 . . . . . 1 2 . . . . . 3 . . . %e A342997 . . . . 3 4 . . . . . 0 . . . . . 1 . . . . . 2 . %e A342997 . 2 . . . . . 3 . . . . . 4 . . . . . 0 1 . . . . %e A342997 . . . 1 . . . . . 2 3 . . . . . 4 . . . . . 0 . . %Y A342997 Cf. A006717, A123565, A287648, A338562, A341585, A342998. %K A342997 nonn,more,hard %O A342997 0,3 %A A342997 _Eduard I. Vatutin_, Apr 02 2021