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 A209591 #8 Jul 22 2025 21:50:25 %S A209591 7,2401,1529437,47738317081,2767247026234327,7860041410116536427241, %T A209591 41461694858240499304086993277,10716805483614568896270487886484563281, %U A209591 5144331626584186407654932265866559478676249287 %N A209591 Number of n X n 0..6 arrays with every element equal to a diagonal or antidiagonal reflection. %C A209591 Column 6 of A209593 %H A209591 R. H. Hardin, <a href="/A209591/b209591.txt">Table of n, a(n) for n = 1..30</a> %F A209591 a(n) = 7 ^ (2*n-(n modulo 2)) * 91 ^ ((n*n-2*n+(n modulo 2))/4) %e A209591 Some solutions for n=3 %e A209591 ..0..5..4....0..0..4....0..6..2....0..6..5....0..3..3....0..3..5....0..3..5 %e A209591 ..5..2..1....0..3..2....6..0..2....5..2..6....3..5..0....2..2..3....3..5..5 %e A209591 ..1..1..3....3..2..5....1..2..1....4..5..3....5..0..1....4..2..0....3..5..3 %K A209591 nonn %O A209591 1,1 %A A209591 _R. H. Hardin_ Mar 10 2012