cp's OEIS Frontend

A217451 Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal and vertical neighbors in a random 0..2 n X 2 array.

%I A217451 #11 Mar 09 2018 19:33:43
%S A217451 3,15,69,253,1049,4205,16887,68015,273471,1100135,4425449,17801365,
%T A217451 71607677,288046417,1158686263,4660895899,18748771139,75418217399,
%U A217451 303374944277,1220346484777,4908927310389,19746496259789,79431633434755
%N A217451 Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal and vertical neighbors in a random 0..2 n X 2 array.
%C A217451 Column 2 of A217457.
%H A217451 R. H. Hardin, <a href="/A217451/b217451.txt">Table of n, a(n) for n = 1..128</a>
%F A217451 Empirical: a(n) = 3*a(n-1) + 3*a(n-2) + 6*a(n-3) - 5*a(n-4) + a(n-5) - 17*a(n-6) - 14*a(n-7) - 26*a(n-8) - 4*a(n-9).
%F A217451 Empirical g.f.: x*(3 + 6*x + 15*x^2 - 17*x^3 + 8*x^4 - 43*x^5 - 12*x^6 - 62*x^7 - 12*x^8) / (1 - 3*x - 3*x^2 - 6*x^3 + 5*x^4 - x^5 + 17*x^6 + 14*x^7 + 26*x^8 + 4*x^9). - _Colin Barker_, Mar 09 2018
%e A217451 Some solutions for n=3:
%e A217451 ..2..2....0..0....0..0....0..0....1..0....2..2....0..0....1..2....0..0....1..0
%e A217451 ..2..1....0..0....0..0....1..0....0..0....0..1....1..0....1..1....2..0....0..0
%e A217451 ..1..1....2..1....2..2....0..0....2..0....0..0....2..2....1..2....0..0....1..0
%Y A217451 Cf. A217457.
%K A217451 nonn
%O A217451 1,1
%A A217451 _R. H. Hardin_, Oct 03 2012