cp's OEIS Frontend

A198909 Number of nX3 0..7 arrays with values 0..7 introduced in row major order and no element equal to any horizontal or vertical neighbor.

%I A198909 #7 Jul 22 2025 13:07:00
%S A198909 2,34,2051,269940,54381563,13088156547,3352514013159,876632051686733,
%T A198909 230783525290600476,60892298359864756053,16078352442288906898825,
%U A198909 4246466444504000973551502,1121629692628918068552449185
%N A198909 Number of nX3 0..7 arrays with values 0..7 introduced in row major order and no element equal to any horizontal or vertical neighbor.
%C A198909 Column 3 of A198914
%H A198909 R. H. Hardin, <a href="/A198909/b198909.txt">Table of n, a(n) for n = 1..200</a>
%F A198909 Empirical: a(n) = 431*a(n-1) -53038*a(n-2) +2570412*a(n-3) -55789402*a(n-4) +610919758*a(n-5) -3707175288*a(n-6) +13010264300*a(n-7) -26380804149*a(n-8) +29517406483*a(n-9) -16243626186*a(n-10) +3246286680*a(n-11)
%e A198909 Some solutions with values 0 to 7 for n=4
%e A198909 ..0..1..2....0..1..2....0..1..2....0..1..0....0..1..2....0..1..2....0..1..2
%e A198909 ..3..4..0....3..4..5....3..0..4....2..3..4....1..3..4....3..0..4....3..4..0
%e A198909 ..5..3..6....4..2..0....5..4..6....3..5..6....5..0..6....4..1..5....5..6..3
%e A198909 ..0..1..7....1..6..7....6..1..7....7..4..0....0..1..7....6..7..4....3..5..7
%K A198909 nonn
%O A198909 1,1
%A A198909 _R. H. Hardin_ Oct 31 2011