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 A196137 #7 Jun 02 2025 04:17:46 %S A196137 3,46,117,931,3288,20706,75720,384083,1662512,8212668,37172701, %T A196137 176457313,803299589,3768617073,17355787464,81234030372,376860933270, %U A196137 1753580102111,8135995110263,37838340282830,175764796211917,817275191103917 %N A196137 Number of nX7 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 0,2,1,3,4 for x=0,1,2,3,4. %C A196137 Every 0 is next to 0 0's, every 1 is next to 1 2's, every 2 is next to 2 1's, every 3 is next to 3 3's, every 4 is next to 4 4's %C A196137 Column 7 of A196138 %H A196137 R. H. Hardin, <a href="/A196137/b196137.txt">Table of n, a(n) for n = 1..142</a> %e A196137 Some solutions for n=4 %e A196137 ..1..2..0..1..1..2..1....1..1..2..2..1..1..0....1..2..1..1..2..2..1 %e A196137 ..0..1..1..2..0..2..1....2..0..1..1..0..2..1....1..2..1..0..1..1..1 %e A196137 ..2..1..1..2..1..1..1....1..1..1..1..2..2..1....1..2..0..1..1..1..2 %e A196137 ..1..0..1..2..1..1..2....1..2..2..1..1..1..0....0..1..1..2..2..1..0 %K A196137 nonn %O A196137 1,1 %A A196137 _R. H. Hardin_ Sep 28 2011