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 A057629 #19 Mar 17 2023 01:38:00 %S A057629 2,8,52,568,10436,323144,16866856,1484714416,220426128584 %N A057629 Number of alternating sign 2n X 2n matrices invariant under flips in both diagonals. %H A057629 D. P. Robbins, <a href="https://arxiv.org/abs/math/0008045">Symmetry classes of alternating sign matrices</a>, arXiv:math/0008045 [math.CO], 2000. %F A057629 a(n) = A005162(2*n). %Y A057629 Even numbered terms of A005162. %Y A057629 Cf. A059475. %K A057629 nonn,more,nice %O A057629 1,1 %A A057629 _N. J. A. Sloane_, Oct 10 2000 %E A057629 a(8)-a(9) from A005162(2*n) by _Jinyuan Wang_, Mar 03 2020