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 A206693 #9 Jul 22 2025 19:37:02 %S A206693 3,81,15712,23335217,262482902920,22540704363210913, %T A206693 14777630573426014735558,74010398585294927963749126971, %U A206693 2831737193779046594636895038867701496 %N A206693 Number of n X n 0..2 arrays avoiding the pattern z-2 z-1 z in any row or column. %C A206693 Diagonal of A206700 %H A206693 R. H. Hardin, <a href="/A206693/b206693.txt">Table of n, a(n) for n = 1..10</a> %e A206693 Some solutions for n=4 %e A206693 ..0..2..2..0....2..0..0..0....2..0..0..1....0..2..0..1....2..1..0..2 %e A206693 ..1..0..0..0....0..1..1..0....1..1..0..1....2..0..1..0....1..1..1..2 %e A206693 ..0..2..1..2....0..1..0..2....2..0..1..0....0..2..1..1....1..1..0..1 %e A206693 ..0..0..0..0....2..2..0..1....1..1..0..0....2..0..0..1....1..1..0..1 %K A206693 nonn %O A206693 1,1 %A A206693 _R. H. Hardin_ Feb 11 2012