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