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 A208862 #7 Jul 22 2025 21:31:59 %S A208862 187,315203,607924387,1179377179523,2289701830963879, %T A208862 4445765748006060562,8632160191264007914496, %U A208862 16760735467624113550972052,32543685580973709708760951442,63188843847651604770766546682829 %N A208862 Number of nX6 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or left-upward diagonal neighbors. %C A208862 Column 6 of A208864 %H A208862 R. H. Hardin, <a href="/A208862/b208862.txt">Table of n, a(n) for n = 1..136</a> %e A208862 Some solutions for n=4 %e A208862 ..0..1..0..0..2..2....0..0..0..0..0..1....0..0..0..0..0..0....0..0..0..0..0..0 %e A208862 ..1..2..1..1..3..3....0..1..2..1..3..2....0..1..1..1..2..1....1..2..1..1..1..3 %e A208862 ..0..3..3..0..1..0....1..3..0..3..1..0....0..1..0..2..3..1....1..3..3..2..2..3 %e A208862 ..2..1..1..2..1..2....2..1..0..3..0..3....0..3..1..0..1..0....0..1..0..0..1..0 %K A208862 nonn %O A208862 1,1 %A A208862 _R. H. Hardin_ Mar 02 2012