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 A209586 #8 Jul 22 2025 21:49:51 %S A209586 2,16,192,9216,663552,191102976,82556485632,142657607172096, %T A209586 369768517790072832,3833759992447475122176,59622635402543133100081152, %U A209586 3709004903121403223889848303616,346094665520064377627609524907016192 %N A209586 Number of n X n 0..1 arrays with every element equal to a diagonal or antidiagonal reflection. %C A209586 Column 1 of A209593 %H A209586 R. H. Hardin, <a href="/A209586/b209586.txt">Table of n, a(n) for n = 1..30</a> %F A209586 a(n) = 2 ^ (2*n-(n modulo 2)) * 6 ^ ((n*n-2*n+(n modulo 2))/4) %e A209586 Some solutions for n=3 %e A209586 ..0..1..0....1..0..0....1..0..0....1..1..1....0..0..1....0..0..0....1..1..1 %e A209586 ..1..1..0....0..0..0....0..0..0....0..1..1....1..0..0....1..1..0....0..1..1 %e A209586 ..0..0..1....1..0..0....0..0..1....1..0..1....0..1..0....0..1..0....1..0..0 %K A209586 nonn %O A209586 1,1 %A A209586 _R. H. Hardin_ Mar 10 2012