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 A207985 #7 Jul 22 2025 21:04:37 %S A207985 69,4761,244325,12271227,622569385,31638012071,1607243845009, %T A207985 81641053794111,4147075467417469,210658289444343157, %U A207985 10700760566367351027,543563676726218129663,27611262828599058482901,1402562262828848350945747 %N A207985 Number of nX4 0..2 arrays avoiding the pattern z z+1 z horizontally and z z-1 z vertically. %C A207985 Column 4 of A207989 %H A207985 R. H. Hardin, <a href="/A207985/b207985.txt">Table of n, a(n) for n = 1..210</a> %e A207985 Some solutions for n=4 %e A207985 ..0..2..2..2....0..2..0..0....0..2..0..1....2..0..0..0....2..2..1..2 %e A207985 ..1..1..0..2....0..1..2..0....2..0..1..1....0..1..1..0....2..1..0..0 %e A207985 ..2..0..1..1....1..0..2..0....0..2..1..1....0..1..1..2....1..1..2..0 %e A207985 ..1..2..0..0....0..2..1..2....2..0..0..1....2..2..0..1....0..1..2..2 %K A207985 nonn %O A207985 1,1 %A A207985 _R. H. Hardin_ Feb 22 2012