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 A251807 #6 Jun 02 2025 10:32:58 %S A251807 305991368,310512400748,114701510008550,20552060379396424, %T A251807 2134102396738819286,144607697103715449366,6950854990205965398511, %U A251807 251944939127223553670932,7212104449092454367810317 %N A251807 Number of (7+1)X(n+1) 0..3 arrays with no 2X2 subblock having x11-x00 less than x10-x01. %C A251807 Row 7 of A251801 %H A251807 R. H. Hardin, <a href="/A251807/b251807.txt">Table of n, a(n) for n = 1..13</a> %e A251807 Some solutions for n=1 %e A251807 ..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0 %e A251807 ..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0 %e A251807 ..0..0....0..0....0..0....0..0....0..0....0..0....0..2....0..2....0..0....0..2 %e A251807 ..2..2....0..2....0..2....0..0....2..2....0..2....0..0....0..0....2..2....2..2 %e A251807 ..2..2....0..2....0..2....1..3....1..3....2..3....0..1....3..3....1..1....2..3 %e A251807 ..2..2....0..3....1..3....0..3....0..3....0..2....0..0....0..0....0..2....1..1 %e A251807 ..3..3....1..2....1..1....1..2....0..2....2..0....0..1....0..3....3..1....0..2 %e A251807 ..0..3....0..0....1..2....2..2....3..1....0..2....2..1....0..0....1..3....3..1 %K A251807 nonn %O A251807 1,1 %A A251807 _R. H. Hardin_, Dec 09 2014