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 A186171 #8 Jul 22 2025 10:17:41 %S A186171 520017,311128593,188034884094,111203560772547,63117570540037053, %T A186171 34184079614729409659,17695100284866122677270, %U A186171 8806300375583656355791730,4233722976051532579394137546,1964837017618166811806637674433 %N A186171 Number of (n+2)X(n+2) 0..5 arrays with each 3X3 subblock having rows and columns in lexicographically nondecreasing order. %C A186171 Diagonal of A186180 %H A186171 R. H. Hardin, <a href="/A186171/b186171.txt">Table of n, a(n) for n = 1..11</a> %e A186171 Some solutions for 4X4 %e A186171 ..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0 %e A186171 ..0..0..0..3....0..0..0..3....0..0..0..3....0..0..0..0....0..0..0..0 %e A186171 ..1..1..1..5....0..0..1..1....0..1..2..5....0..1..4..5....0..1..2..3 %e A186171 ..1..1..2..5....0..3..1..0....5..3..5..4....0..4..4..0....0..4..4..5 %K A186171 nonn %O A186171 1,1 %A A186171 _R. H. Hardin_ Feb 13 2011