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 A195798 #17 Sep 08 2022 11:55:22 %S A195798 1,1,2,8,16,64,1184,5300,130324,14748808,421963232,54990266540 %N A195798 Number of triangular n X n X n 0..1 arrays with all rows and diagonals having the same length having the same sum, with corners zero. %C A195798 From _Pontus von Brömssen_, Sep 08 2022: (Start) %C A195798 For n <= 6, all solutions are rotationally symmetric, which implies that a(n) = 2^(A007997(n+4)-1). But for n >= 7 there exist asymmetric solutions like %C A195798 0 %C A195798 0 0 %C A195798 0 0 1 %C A195798 0 1 0 0 %C A195798 1 0 0 0 0 %C A195798 0 0 0 0 1 0 %C A195798 0 0 0 1 0 0 0. %C A195798 (End) %e A195798 Some solutions for n=5 %e A195798 ......0..........0..........0..........0..........0..........0..........0 %e A195798 .....0.0........0.0........0.0........0.1........0.1........0.1........0.1 %e A195798 ....0.1.0......1.0.1......1.1.1......0.0.0......0.1.0......1.0.1......1.1.1 %e A195798 ...0.1.1.0....0.0.0.0....0.1.1.0....1.0.0.0....1.1.1.0....1.0.0.0....1.1.1.0 %e A195798 ..0.0.0.0.0..0.0.1.0.0..0.0.1.0.0..0.0.0.1.0..0.0.0.1.0..0.0.1.1.0..0.0.1.1.0 %Y A195798 Column 1 of A195805. %Y A195798 Cf. A007997. %K A195798 nonn,hard,more %O A195798 1,3 %A A195798 _R. H. Hardin_, Sep 23 2011