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 A198718 #7 Jul 22 2025 13:05:54 %S A198718 2,34,2027,232841,34003792,5315840795,846047363854,135284283124811, %T A198718 21658679381667910,3468618095206638077,555543217744635684040, %U A198718 88979288917879960297469,14251565534424509235823960 %N A198718 Number of nX3 0..6 arrays with values 0..6 introduced in row major order and no element equal to any horizontal or vertical neighbor. %C A198718 Column 3 of A198723 %H A198718 R. H. Hardin, <a href="/A198718/b198718.txt">Table of n, a(n) for n = 1..200</a> %F A198718 Empirical: a(n) = 234*a(n-1) -13497*a(n-2) +283640*a(n-3) -2626919*a(n-4) +12277210*a(n-5) -30282843*a(n-6) +38629620*a(n-7) -23115780*a(n-8) +4848336*a(n-9) %e A198718 Some solutions with all values 0 to 6 for n=4 %e A198718 ..0..1..2....0..1..2....0..1..2....0..1..2....0..1..2....0..1..0....0..1..2 %e A198718 ..3..0..4....3..0..3....3..4..3....3..2..0....3..4..5....2..3..4....3..4..5 %e A198718 ..5..3..5....4..5..2....4..5..6....4..5..3....5..6..4....1..0..5....4..6..4 %e A198718 ..2..6..2....2..0..6....5..1..5....1..6..0....0..5..1....6..2..4....3..4..6 %K A198718 nonn %O A198718 1,1 %A A198718 _R. H. Hardin_ Oct 29 2011