cp's OEIS Frontend

A217958 Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random 0..2 n X 2 array.

%I A217958 #7 Jul 23 2018 13:43:49
%S A217958 3,17,77,343,1523,6761,30013,133231,591427,2625409,11654477,51735495,
%T A217958 229659507,1019483609,4525598973,20089627615,89180048899,395879967217,
%U A217958 1757354367693,7801087777591,34629879796851,153725814775369
%N A217958 Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random 0..2 n X 2 array.
%C A217958 Column 2 of A217964.
%H A217958 R. H. Hardin, <a href="/A217958/b217958.txt">Table of n, a(n) for n = 1..179</a>
%F A217958 Empirical: a(n) = 4*a(n-1) + 2*a(n-2) - a(n-4).
%F A217958 Empirical g.f.: x*(1 + x)*(3 + 2*x + x^2) / (1 - 4*x - 2*x^2 + x^4). - _Colin Barker_, Jul 23 2018
%e A217958 Some solutions for n=3:
%e A217958 ..0..0....0..0....2..2....1..0....2..1....1..1....2..2....2..1....2..2....0..0
%e A217958 ..0..0....1..2....2..2....0..0....1..0....2..2....2..2....1..1....1..0....0..2
%e A217958 ..0..2....1..1....0..0....0..2....0..0....1..1....2..2....0..0....0..0....2..2
%Y A217958 Cf. A217964.
%K A217958 nonn
%O A217958 1,1
%A A217958 _R. H. Hardin_, Oct 16 2012