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 A209018 #7 Jul 22 2025 21:35:05 %S A209018 2916,20918008,148774643618,1057701934285612,7521858792951566188, %T A209018 53490209804089514438574,380386826513820237531618354, %U A209018 2705056288752965649168385141630,19236551636169391849856640820638184 %N A209018 Number of nX7 0..3 arrays with no element equal the average of immediate neighbors vertically above, diagonally above and left, and horizontally left of it. %C A209018 Column 7 of A209019 %H A209018 R. H. Hardin, <a href="/A209018/b209018.txt">Table of n, a(n) for n = 1..210</a> %e A209018 Some solutions for n=4 %e A209018 ..1..3..0..1..2..3..2....2..3..1..2..1..2..3....1..3..2..3..0..1..3 %e A209018 ..2..0..2..2..1..1..0....3..0..3..3..0..2..3....3..0..0..3..1..3..3 %e A209018 ..1..2..2..3..1..0..0....2..1..1..2..1..2..0....2..0..1..2..0..3..0 %e A209018 ..3..0..0..1..1..1..3....3..0..3..0..0..2..1....1..2..0..3..0..2..3 %K A209018 nonn %O A209018 1,1 %A A209018 _R. H. Hardin_ Mar 04 2012