cp's OEIS Frontend

A218517 Number of n X 3 arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random 0..3 n X 3 array.

%I A218517 #7 Jul 24 2018 09:40:04
%S A218517 16,286,4634,76214,1254462,20655650,340133516,5601018048,92232936766,
%T A218517 1518816980614,25010647012824,411855079591306,6782095959978908,
%U A218517 111682064830460636,1839089815861812230,30284641999299892776
%N A218517 Number of n X 3 arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random 0..3 n X 3 array.
%C A218517 Column 3 of A218522.
%H A218517 R. H. Hardin, <a href="/A218517/b218517.txt">Table of n, a(n) for n = 1..157</a>
%F A218517 Empirical: a(n) = 18*a(n-1) - 19*a(n-2) - 96*a(n-3) - 112*a(n-4) - a(n-5) + 140*a(n-6) + 64*a(n-7).
%F A218517 Empirical g.f.: 2*x*(8 - x - 105*x^2 - 114*x^3 - 48*x^4 + 156*x^5 + 96*x^6) / (1 - 18*x + 19*x^2 + 96*x^3 + 112*x^4 + x^5 - 140*x^6 - 64*x^7). - _Colin Barker_, Jul 24 2018
%e A218517 Some solutions for n=3:
%e A218517 ..0..0..1....2..0..3....3..2..2....2..2..3....0..0..0....0..0..1....1..1..1
%e A218517 ..0..0..0....0..0..1....2..1..1....2..2..0....2..0..1....3..1..1....2..1..2
%e A218517 ..1..0..1....2..0..0....2..1..3....0..0..0....3..0..0....1..1..3....1..1..2
%Y A218517 Cf. A218522.
%K A218517 nonn
%O A218517 1,1
%A A218517 _R. H. Hardin_, Oct 31 2012