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 A184539 #8 Jul 22 2025 09:37:10 %S A184539 45,193,631,1837,5313,16345,54543,194245,719905,2725367,10430675, %T A184539 40158073,155173369,601154073,2333701711,9075257125,35345417073, %U A184539 137846719279,538258108483,2104099248441,8233431070825,32247604093423 %N A184539 Number of (n+2)X(n+2) binary arrays with each 3X3 subblock having rows and columns in lexicographically nondecreasing order. %C A184539 Diagonal of A184548 %H A184539 R. H. Hardin, <a href="/A184539/b184539.txt">Table of n, a(n) for n = 1..68</a> %e A184539 Some solutions for 4X4 %e A184539 ..0..0..1..1....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..1 %e A184539 ..0..0..1..1....0..0..0..1....0..0..0..0....0..0..0..1....0..1..1..1 %e A184539 ..1..1..0..1....0..0..1..1....0..0..1..1....0..0..0..1....0..1..1..1 %e A184539 ..1..1..0..1....0..0..1..1....1..1..0..0....0..0..0..1....0..1..1..1 %K A184539 nonn %O A184539 1,1 %A A184539 _R. H. Hardin_ Jan 16 2011