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%I #7 Oct 29 2018 10:05:00
%S 2,3,2,10,18,18,46,58,102,173,264,487,738,1318,2151,3591,6192,10096,
%T 17480,28925,49131,82966,138977,236535,395979,671706,1131018,1908201,
%U 3226558,5432423,9189152,15486612,26156656,44151446,74485403,125808822
%N Number of 2 X n 0..3 arrays with no element equal to one plus the sum of elements to its left or zero plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4.
%H R. H. Hardin, <a href="/A241055/b241055.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 3*a(n-2) + 3*a(n-3) - 3*a(n-4) - 4*a(n-5) - 2*a(n-6) + 3*a(n-7) - a(n-9) + 2*a(n-11) - 2*a(n-12) + 2*a(n-15) for n>17.
%F Empirical g.f.: x*(2 + 3*x - 4*x^2 - 5*x^3 + 9*x^4 - x^5 - 16*x^6 - 12*x^7 - x^8 + 3*x^9 + 3*x^10 + 11*x^12 - 10*x^13 - 8*x^14 + 6*x^15 + 8*x^16) / ((1 - x)*(1 + x - 2*x^2 - 5*x^3 - 2*x^4 + 2*x^5 + 4*x^6 + x^7 + x^8 + 2*x^9 + 2*x^10 + 2*x^12 + 2*x^13 + 2*x^14)). - _Colin Barker_, Oct 29 2018
%e Some solutions for n=4:
%e ..3..3..2..2....3..3..2..2....3..2..3..3....3..2..3..3....3..3..2..2
%e ..2..1..1..3....2..2..0..0....2..1..1..0....2..1..1..2....2..2..0..3
%Y Row 2 of A241054.
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 15 2014