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 A197671 #7 Jun 02 2025 05:04:44 %S A197671 25,1963,74812,3675345,178113620,8613257822,417293944115, %T A197671 20252638815131,981414876628367,47569549221404522,2306162325188337684, %U A197671 111794015697526614448,5419263655984491978357,262704965350074163519109 %N A197671 Number of nX7 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 4,0,1,0,1 for x=0,1,2,3,4. %C A197671 Every 0 is next to 0 4's, every 1 is next to 1 0's, every 2 is next to 2 1's, every 3 is next to 3 0's, every 4 is next to 4 1's %C A197671 Column 7 of A197672 %H A197671 R. H. Hardin, <a href="/A197671/b197671.txt">Table of n, a(n) for n = 1..33</a> %e A197671 Some solutions containing all values 0 to 4 for n=4 %e A197671 ..0..3..0..2..1..0..1....0..0..2..1..1..1..1....0..3..0..2..1..0..0 %e A197671 ..0..0..0..1..4..1..1....1..1..1..0..0..0..0....3..0..0..1..4..1..1 %e A197671 ..0..3..0..2..1..1..0....1..1..4..1..3..0..3....0..3..0..1..1..1..2 %e A197671 ..1..1..0..0..0..2..1....0..0..1..1..0..0..0....1..2..1..1..0..0..0 %K A197671 nonn %O A197671 1,1 %A A197671 _R. H. Hardin_ Oct 17 2011