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 A198719 #7 Jul 22 2025 13:06:02 %S A198719 5,499,232841,173549032,141168480719,116492275674072, %T A198719 96356630422085931,79732515488691835557,65980773070548173552412, %U A198719 54601426682639992758644080,45184694908666112938858073903,37392013011256643009627621268829 %N A198719 Number of nX4 0..6 arrays with values 0..6 introduced in row major order and no element equal to any horizontal or vertical neighbor. %C A198719 Column 4 of A198723 %H A198719 R. H. Hardin, <a href="/A198719/b198719.txt">Table of n, a(n) for n = 1..200</a> %F A198719 Empirical: a(n) = 1081*a(n-1) -231028*a(n-2) +18466747*a(n-3) -729356901*a(n-4) +16017483310*a(n-5) -207602672167*a(n-6) +1633653422655*a(n-7) -7862297151184*a(n-8) +22902587520657*a(n-9) -39383752489643*a(n-10) +38480449661142*a(n-11) -19517387256516*a(n-12) +3939042601848*a(n-13) %e A198719 Some solutions with all values 0 to 6 for n=5 %e A198719 ..0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1 %e A198719 ..1..0..1..0....1..0..1..0....1..0..1..0....1..0..1..0....1..0..1..0 %e A198719 ..0..2..0..1....2..1..0..1....2..3..0..1....2..3..0..1....2..3..0..1 %e A198719 ..3..4..1..4....1..0..3..4....4..5..6..3....4..5..4..5....1..0..4..2 %e A198719 ..5..6..4..0....5..4..0..6....6..0..4..0....0..4..6..1....4..5..3..6 %K A198719 nonn %O A198719 1,1 %A A198719 _R. H. Hardin_ Oct 29 2011