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%I #7 Oct 12 2018 11:30:56
%S 61,307,1543,7783,39331,199003,1007683,5105107,25871611,131138323,
%T 664800571,3370454419,17088658027,86644639459,439323545083,
%U 2227578407827,11294972125867,57271642785859,290399314134427,1472490373513267
%N Number of (n+1) X (1+1) 0..4 arrays with every 2 X 2 subblock having the absolute values of all six edge and diagonal differences no larger than 1.
%H R. H. Hardin, <a href="/A234029/b234029.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 7*a(n-1) - 6*a(n-2) - 18*a(n-3) - 6*a(n-4).
%F Empirical g.f.: x*(61 - 120*x - 240*x^2 - 78*x^3) / (1 - 7*x + 6*x^2 + 18*x^3 + 6*x^4). - _Colin Barker_, Oct 12 2018
%e Some solutions for n=5:
%e ..4..4....3..4....3..3....4..4....0..1....2..2....3..2....1..2....1..2....1..2
%e ..3..3....3..3....3..3....3..3....0..1....2..1....3..3....2..2....2..2....2..1
%e ..2..2....3..2....4..3....3..3....1..1....1..1....3..2....2..2....3..3....1..1
%e ..1..1....2..3....3..4....2..2....2..1....1..1....3..3....2..1....3..2....1..0
%e ..1..0....3..3....3..4....3..3....2..2....2..1....3..3....1..2....2..2....1..1
%e ..1..0....2..3....3..4....3..4....3..3....1..1....4..3....2..1....2..2....2..1
%Y Column 1 of A234036.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 18 2013
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