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 A196956 #7 Sep 04 2022 11:13:13 %S A196956 13,178,2987,78717,1918608,46887039,1147966466,28133304588, %T A196956 688970472958,16871844816740,413232005901840,10120704139954048, %U A196956 247866954036866195,6070590513451031047,148677076483267579402,3641296772946640910171 %N A196956 Number of n X 7 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,1,3,4,0 for x=0,1,2,3,4. %C A196956 Every 0 is next to 0 2's, every 1 is next to 1 1's, every 2 is next to 2 3's, every 3 is next to 3 4's, every 4 is next to 4 0's. %C A196956 Column 7 of A196957. %H A196956 R. H. Hardin, <a href="/A196956/b196956.txt">Table of n, a(n) for n = 1..200</a> %e A196956 Some solutions for n=4 %e A196956 ..1..1..0..0..0..0..1....0..0..1..0..0..1..0....1..0..0..1..0..1..0 %e A196956 ..0..0..0..0..0..0..1....0..0..1..0..0..1..0....1..0..0..1..0..1..0 %e A196956 ..1..0..0..0..0..0..0....0..4..0..0..4..0..1....0..0..0..0..4..0..1 %e A196956 ..1..0..1..1..0..1..1....0..0..1..1..0..0..1....1..1..0..0..0..0..1 %Y A196956 Cf. A196957. %K A196956 nonn %O A196956 1,1 %A A196956 _R. H. Hardin_, Oct 08 2011