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 A198907 #11 Jul 22 2025 13:06:53
%S A198907 1,4,2051,319608038,4717456775959530,2869765342757082981876352
%N A198907 Number of n X n 0..7 arrays with values 0..7 introduced in row major order and no element equal to any horizontal or vertical neighbor.
%C A198907 Diagonal of A198914
%H A198907 Jean-François Alcover, <a href="/A198907/b198907.txt">Table of n, a(n) for n = 1..12</a>
%e A198907 Some solutions with values 0 to 7 for n=3
%e A198907 ..0..1..2....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2
%e A198907 ..3..4..5....3..4..5....3..4..5....3..4..1....3..4..5....3..4..5....3..4..5
%e A198907 ..6..7..4....1..6..7....4..6..7....5..6..7....2..6..7....6..0..7....6..2..7
%t A198907 A198914 = Cases[Import["https://oeis.org/A198914/b198914.txt", "Table"], {_, _}][[All, 2]];
%t A198907 a[n_] := A198914[[2 n^2 - 2 n + 1]];
%t A198907 Table[a[n], {n, 1, 12}] (* _Jean-François Alcover_, Sep 23 2019 *)
%K A198907 nonn
%O A198907 1,2
%A A198907 _R. H. Hardin_ Oct 31 2011