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 A219305 #6 Jul 23 2025 00:21:47 %S A219305 4,18,90,423,1958,9233,43725,206269,971794,4583164,21622807,101988408, %T A219305 481001317,2268654909,10700463129,50469641870,238042556300, %U A219305 1122743524739,5295505220276,24976631418525,117804014337453,555630918690165 %N A219305 Unchanging value maps: number of nX3 binary arrays indicating the locations of corresponding elements unequal to no horizontal or vertical neighbor in a random 0..2 nX3 array. %C A219305 Column 3 of A219310 %H A219305 R. H. Hardin, <a href="/A219305/b219305.txt">Table of n, a(n) for n = 1..95</a> %F A219305 Empirical: a(n) = 4*a(n-1) +a(n-2) +7*a(n-3) +35*a(n-4) -60*a(n-5) -68*a(n-6) +93*a(n-7) -72*a(n-8) -111*a(n-9) +101*a(n-10) -21*a(n-11) -28*a(n-12) +32*a(n-13) +2*a(n-14) +6*a(n-15) +8*a(n-16) %e A219305 Some solutions for n=3 %e A219305 ..1..0..1....0..0..0....1..1..1....1..1..1....0..0..1....0..0..0....0..0..1 %e A219305 ..0..0..0....0..0..0....0..0..0....1..1..0....1..0..0....0..0..0....0..0..1 %e A219305 ..0..1..0....0..0..1....0..0..0....1..0..0....1..0..0....1..1..0....1..0..0 %K A219305 nonn %O A219305 1,1 %A A219305 _R. H. Hardin_ Nov 17 2012