cp's OEIS Frontend

A239980 Number of n X 2 0..3 arrays with no element equal to zero plus the sum of elements to its left or two plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest, modulo 4.

%I A239980 #12 Oct 26 2018 14:30:58
%S A239980 1,3,6,16,40,84,208,474,1047,2530,5668,12907,30446,68427,157875,
%T A239980 366480,830089,1920870,4421253,10083067,23303103,53453752,122448587,
%U A239980 282350403,647215090,1486007814,3420002865,7842656682,18022838258,41428828907
%N A239980 Number of n X 2 0..3 arrays with no element equal to zero plus the sum of elements to its left or two plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest, modulo 4.
%H A239980 R. H. Hardin, <a href="/A239980/b239980.txt">Table of n, a(n) for n = 1..210</a>
%F A239980 Empirical: a(n) = 2*a(n-2) + 10*a(n-3) - a(n-4) - 5*a(n-5) - 15*a(n-6) + a(n-7) + 4*a(n-8) + 2*a(n-9) + 10*a(n-10) + 5*a(n-11) - 6*a(n-13).
%F A239980 Empirical g.f.: x*(1 + 3*x + 4*x^2 - x^4 + 4*x^6 - 4*x^7 - 6*x^8 + 6*x^9 + 6*x^10 - 4*x^12) / (1 - 2*x^2 - 10*x^3 + x^4 + 5*x^5 + 15*x^6 - x^7 - 4*x^8 - 2*x^9 - 10*x^10 - 5*x^11 + 6*x^13). - _Colin Barker_, Oct 26 2018
%e A239980 Some solutions for n=4:
%e A239980 ..3..0....3..0....3..0....3..0....3..0....3..0....3..0....3..0....3..0....3..0
%e A239980 ..2..1....2..1....2..1....2..3....2..1....3..1....3..1....3..1....2..1....2..1
%e A239980 ..2..1....2..0....2..0....2..0....2..1....2..1....3..2....3..1....2..1....2..0
%e A239980 ..3..2....3..1....3..0....3..2....3..1....3..1....2..3....2..1....2..1....3..2
%Y A239980 Column 2 of A239986.
%K A239980 nonn
%O A239980 1,2
%A A239980 _R. H. Hardin_, Mar 30 2014