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A221246 Number of 2 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor.

%I A221246 #9 Aug 04 2018 14:32:42
%S A221246 0,9,50,484,3864,32400,267264,2214144,18316800,151585344,1254325824,
%T A221246 10379534400,85889605824,710729930304,5881230244800,48666696727104,
%U A221246 402712880117184,3332415765326400,27575464553486784,228184686537228864
%N A221246 Number of 2 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor.
%C A221246 Row 2 of A221245.
%H A221246 R. H. Hardin, <a href="/A221246/b221246.txt">Table of n, a(n) for n = 1..210</a>
%F A221246 Empirical: a(n) = 9*a(n-1) - 54*a(n-3) + 36*a(n-4) for n>5.
%F A221246 Empirical g.f.: x^2*(9 - 31*x + 34*x^2 - 6*x^3) / ((1 - 9*x + 6*x^2)*(1 - 6*x^2)). - _Colin Barker_, Aug 04 2018
%e A221246 Some solutions for n=3:
%e A221246   1 3 1   0 3 0   2 2 0   0 4 2   0 2 0   1 4 1   0 2 2
%e A221246   0 1 0   0 1 2   0 2 0   0 0 0   1 2 1   0 0 0   0 2 0
%Y A221246 Cf. A221245.
%K A221246 nonn
%O A221246 1,2
%A A221246 _R. H. Hardin_, Jan 06 2013