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 A196451 #7 Jun 02 2025 04:24:21 %S A196451 4,14,40,131,383,1232,3966,12314,38745,122989,386667,1216157,3839910, %T A196451 12101854,38109643,120144068,378709117,1193259020,3760674157, %U A196451 11852918903,37353389828,117718989595,371005905259,1169236902187,3684870558556 %N A196451 Number of nX3 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 3,0,2,4,1 for x=0,1,2,3,4. %C A196451 Every 0 is next to 0 3's, every 1 is next to 1 0's, every 2 is next to 2 2's, every 3 is next to 3 4's, every 4 is next to 4 1's %C A196451 Column 3 of A196456 %H A196451 R. H. Hardin, <a href="/A196451/b196451.txt">Table of n, a(n) for n = 1..200</a> %F A196451 Empirical: a(n) = 4*a(n-1) -5*a(n-2) +15*a(n-3) -28*a(n-4) +13*a(n-5) -a(n-6) -8*a(n-7) +6*a(n-8) +12*a(n-9) -46*a(n-10) +27*a(n-11) -28*a(n-12) +83*a(n-13) -5*a(n-14) +25*a(n-15) -23*a(n-16) -4*a(n-18) %e A196451 Some solutions for n=4 %e A196451 ..0..0..1....1..0..1....0..0..0....0..2..2....1..1..0....0..0..0....0..2..2 %e A196451 ..0..0..1....1..0..1....0..2..2....0..2..2....0..1..1....1..1..1....0..2..2 %e A196451 ..2..2..1....1..2..2....0..2..2....0..1..1....0..2..2....1..1..1....0..0..0 %e A196451 ..2..2..0....0..2..2....0..0..1....1..1..0....0..2..2....0..0..0....1..1..1 %K A196451 nonn %O A196451 1,1 %A A196451 _R. H. Hardin_ Oct 02 2011