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 A348130 #15 Oct 07 2021 00:19:18 %S A348130 1,4,44,1024,34568,1535440,84871680,5613017128,432539436508, %T A348130 38053315307904,3763518275715424 %N A348130 Number of ways to place n nonattacking queens on a 2n X 2n board. %F A348130 a(n) = A348129(2n,n). %e A348130 a(1) = 4: %e A348130 +-----+ +-----+ +-----+ +-----+ %e A348130 | Q . | | . . | | . Q | | . . | %e A348130 | . . | | Q . | | . . | | . Q | %e A348130 +-----+ +-----+ +-----+ +-----+ . %Y A348130 Cf. A348129. %K A348130 nonn,hard,more %O A348130 0,2 %A A348130 _Alois P. Heinz_, Oct 01 2021 %E A348130 a(9)-a(10) from _Martin Ehrenstein_, Oct 06 2021