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 A207988 #7 Jul 22 2025 21:05:25 %S A207988 1465,2146225,1889730415,1607243845009,1389619561706920, %T A207988 1204494622138201455,1043523305166893694120,903935606226751254974991, %U A207988 783031438431844846908049583,678304096543940446283085485892 %N A207988 Number of nX7 0..2 arrays avoiding the pattern z z+1 z horizontally and z z-1 z vertically. %C A207988 Column 7 of A207989 %H A207988 R. H. Hardin, <a href="/A207988/b207988.txt">Table of n, a(n) for n = 1..134</a> %e A207988 Some solutions for n=4 %e A207988 ..0..1..1..2..2..2..0....0..2..2..1..1..2..2....2..0..0..0..2..0..0 %e A207988 ..1..2..0..1..1..2..2....1..2..0..1..1..2..2....1..1..1..0..1..2..2 %e A207988 ..0..1..2..0..0..2..1....1..0..1..2..0..1..1....1..0..1..1..0..0..2 %e A207988 ..0..0..0..0..2..2..1....2..0..2..2..2..1..0....0..0..0..0..2..1..0 %K A207988 nonn %O A207988 1,1 %A A207988 _R. H. Hardin_ Feb 22 2012