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 A208298 #7 Jun 02 2025 07:43:19 %S A208298 5,602,373780,656404264,2475181138384,17131843186425504, %T A208298 196551307092757144384,3478554309451804194287232, %U A208298 90015726535715347904300537088,3267494997828691666636390741293568 %N A208298 Number of nX4 nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal or antidiagonal neighbor (colorings ignoring permutations of colors). %C A208298 Column 4 of A208301 %H A208298 R. H. Hardin, <a href="/A208298/b208298.txt">Table of n, a(n) for n = 1..20</a> %e A208298 Some solutions for n=4 %e A208298 ..0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1 %e A208298 ..0..1..0..1....0..1..0..2....0..1..0..1....0..1..0..1....2..1..0..1 %e A208298 ..2..1..0..2....2..1..0..1....2..1..0..1....0..1..0..1....0..2..0..1 %e A208298 ..0..1..0..1....0..1..0..2....0..1..0..1....2..3..0..1....0..1..0..1 %K A208298 nonn %O A208298 1,1 %A A208298 _R. H. Hardin_ Feb 25 2012