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 A005162 M0877 #32 Aug 27 2023 19:36:56 %S A005162 1,2,3,8,15,52,126,568,1782,10436,42471,323144,1706562,16866856, %T A005162 115640460,1484714416,13216815036,220426128584,2548124192970 %N A005162 Number of alternating sign n X n matrices symmetric with respect to both diagonals. %D A005162 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %D A005162 R. P. Stanley, A baker's dozen of conjectures concerning plane partitions, pp. 285-293 of "Combinatoire Enumerative (Montreal 1985)", Lect. Notes Math. 1234, 1986. %H A005162 Mireille Bousquet-Mélou and Laurent Habsieger, <a href="https://doi.org/10.1016/0012-365X(94)00125-3">Sur les matrices à signes alternants</a>, [On alternating-sign matrices] in Formal power series and algebraic combinatorics (Montreal, PQ, 1992) pp. 19-32; Discrete Math. 139 (1995), 57-72. See Table 1, p. 71. %H A005162 D. P. Robbins, <a href="https://arxiv.org/abs/math/0008045">Symmetry classes of alternating sign matrices</a>, arXiv:math/0008045 [math.CO], 2000. %H A005162 R. P. Stanley, <a href="/A005130/a005130.pdf">A baker's dozen of conjectures concerning plane partitions</a>, pp. 285-293 of "Combinatoire Enumerative (Montreal 1985)", Lect. Notes Math. 1234, 1986. Preprint. [Annotated scanned copy] %F A005162 Robbins gives a simple (conjectured) formula. %K A005162 nonn,nice,more %O A005162 1,2 %A A005162 _N. J. A. Sloane_ and _Simon Plouffe_