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 A207987 #7 Jul 22 2025 21:05:18 %S A207987 529,279841,95527856,31638012071,10629041648848,3578849222737632, %T A207987 1204494622138201455,405333113827258812431,136403423286792425969870, %U A207987 45903034302323213277967472,15447463885373895264608054021 %N A207987 Number of nX6 0..2 arrays avoiding the pattern z z+1 z horizontally and z z-1 z vertically. %C A207987 Column 6 of A207989 %H A207987 R. H. Hardin, <a href="/A207987/b207987.txt">Table of n, a(n) for n = 1..210</a> %e A207987 Some solutions for n=4 %e A207987 ..2..0..2..1..1..1....2..2..2..1..2..2....2..2..1..2..0..0....1..1..1..2..0..2 %e A207987 ..1..0..0..1..2..2....0..2..2..0..0..2....2..0..0..2..2..2....2..0..1..1..0..1 %e A207987 ..0..0..0..2..0..2....1..0..1..2..0..2....1..1..0..2..2..0....1..2..2..1..0..0 %e A207987 ..2..0..1..1..0..0....0..2..0..2..0..2....1..0..1..2..0..2....0..1..2..2..0..2 %K A207987 nonn %O A207987 1,1 %A A207987 _R. H. Hardin_ Feb 22 2012