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 A198905 #7 Jul 22 2025 13:06:46 %S A198905 187,804833,3794115705,17895005957823,84402688527136201, %T A198905 398089706066811447174,1877611081501313948217870, %U A198905 8855851690895754550489882369,41769091588504560613470987916898 %N A198905 Number of nX7 0..4 arrays with values 0..4 introduced in row major order and no element equal to any horizontal or vertical neighbor. %C A198905 Column 7 of A198906 %H A198905 R. H. Hardin, <a href="/A198905/b198905.txt">Table of n, a(n) for n = 1..27</a> %e A198905 Some solutions with values 0 to 4 for n=4 %e A198905 ..0..1..0..1..0..2..3....0..1..0..1..0..2..0....0..1..0..1..0..2..1 %e A198905 ..1..0..1..0..1..3..2....1..0..1..0..3..0..2....1..0..1..0..3..4..3 %e A198905 ..0..1..0..2..0..2..3....0..1..0..2..4..2..4....0..1..0..2..0..1..0 %e A198905 ..1..0..2..0..2..4..1....1..0..2..0..2..1..3....1..0..2..0..2..0..2 %K A198905 nonn %O A198905 1,1 %A A198905 _R. H. Hardin_ Oct 31 2011