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 A381626 #10 Apr 09 2025 07:45:57 %S A381626 0,48,92160,1981808640,1735113100492800 %N A381626 Number of horizontal plane Brown's diagonal Latin squares of order 2n. %C A381626 Brown's diagonal Latin square is a horizontally symmetric row-inverse (horizontal plane Brown's diagonal Latin square) or vertically symmetric column-inverse diagonal Latin square (vertical plane Brown's diagonal Latin square). Diagonal Latin squares of this type have interesting properties, for example, a large number of transversals. %C A381626 Also number of vertical plane Brown's diagonal Latin squares of order 2n with the first row in order. %C A381626 Plain symmetry diagonal Latin squares do not exist for odd orders. %H A381626 E. I. Vatutin, <a href="http://evatutin.narod.ru/evatutin_dls_spec_types_list.pdf">Special types of diagonal Latin squares</a>, Cloud and distributed computing systems in electronic control conference, within the National supercomputing forum (NSCF - 2022), Pereslavl-Zalessky, 2023, pp. 9-18 (in Russian). %H A381626 Eduard I. Vatutin, <a href="https://vk.com/wall162891802_1471">Enumeration of the Brown's diagonal Latin squares of orders 1-9</a> (in Russian). %H A381626 Eduard I. Vatutin, <a href="https://vk.com/wall162891802_2894">Clarification for Brown's diagonal Latin squares for orders 6 and 8</a> (in Russian). %H A381626 <a href="/index/La#Latin">Index entries for sequences related to Latin squares and rectangles</a>. %F A381626 a(n) = A379145(n) * (2n)!. %Y A381626 Cf. A292516, A339641, A340186, A379145. %K A381626 nonn,more,hard %O A381626 1,2 %A A381626 _Eduard I. Vatutin_, Mar 02 2025 %E A381626 a(5) added by Oleg S. Zaikin and _Eduard I. Vatutin_, Apr 08 2025