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 A196949 #7 Jun 02 2025 04:38:26 %S A196949 40,6440,393585,33344883,2668162530,215125975535,17331168379114, %T A196949 1396952062795238,112594151426879227,9074527226180787949, %U A196949 731362786510896873672,58944855804404539921648,4750716841801426807499533 %N A196949 Number of nX7 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 4,1,0,2,3 for x=0,1,2,3,4. %C A196949 Every 0 is next to 0 4's, every 1 is next to 1 1's, every 2 is next to 2 0's, every 3 is next to 3 2's, every 4 is next to 4 3's %C A196949 Column 7 of A196950 %H A196949 R. H. Hardin, <a href="/A196949/b196949.txt">Table of n, a(n) for n = 1..38</a> %e A196949 Some solutions for n=4 %e A196949 ..0..0..0..0..0..0..2....0..0..0..0..2..0..2....0..0..0..2..0..2..1 %e A196949 ..0..0..0..0..0..0..0....0..0..0..0..2..0..0....0..0..0..1..1..0..1 %e A196949 ..0..0..0..0..0..0..1....0..0..0..1..1..0..2....0..0..0..2..0..0..0 %e A196949 ..0..1..1..0..0..0..1....0..1..1..0..0..1..1....0..0..0..1..1..0..0 %K A196949 nonn %O A196949 1,1 %A A196949 _R. H. Hardin_ Oct 08 2011