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 A198720 #7 Jul 22 2025 13:06:10 %S A198720 15,10507,34003792,141168480719,601755060211186,2572072097029554676, %T A198720 10996875674843226590993,47018449018254334323435148, %U A198720 201033586140960282012089201427,859545914195473034723104861028749 %N A198720 Number of nX5 0..6 arrays with values 0..6 introduced in row major order and no element equal to any horizontal or vertical neighbor. %C A198720 Column 5 of A198723 %H A198720 R. H. Hardin, <a href="/A198720/b198720.txt">Table of n, a(n) for n = 1..52</a> %e A198720 Some solutions with all values 0 to 6 for n=3 %e A198720 ..0..1..2..1..3....0..1..2..3..4....0..1..0..2..3....0..1..2..3..4 %e A198720 ..1..0..4..0..5....1..0..1..5..1....1..0..4..5..6....1..0..3..5..3 %e A198720 ..0..2..0..6..1....0..6..0..4..0....0..3..0..4..0....0..4..5..6..0 %K A198720 nonn %O A198720 1,1 %A A198720 _R. H. Hardin_ Oct 29 2011