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 A355256 #30 Aug 08 2025 09:07:06 %S A355256 1,3,47,2544,6480,5510592 %N A355256 a(n) is the number of n-th order n X n magic arrays composed of the numbers from 1 to n^2 in which each 2 X 2 subsquare has the same sum, counted up to rotations and reflections. %H A355256 Donghwi Park, <a href="https://github.com/gwahak/mathematics/blob/master/submagic%20square.ipynb">Source code for a(1) to a(5)</a>. %H A355256 Donghwi Park, <a href="https://github.com/gwahak/mathematics/blob/master/A355256(6).ipynb">Source code for a(6)</a>. %e A355256 For n = 2 the a(2) = 3 solutions are (1 2; 3 4), (1 2; 4 3) and (1 3; 4 2). %K A355256 nonn,more %O A355256 1,2 %A A355256 _Donghwi Park_, Jun 26 2022 %E A355256 a(6) from _Donghwi Park_, Aug 06 2025