cp's OEIS Frontend

A240789 Number of n X 2 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of elements above it or zero plus the sum of the elements diagonally to its northwest or zero plus the sum of the elements antidiagonally to its northeast, modulo 4.

%I A240789 #9 Oct 29 2018 06:43:02
%S A240789 3,4,5,10,13,14,30,32,36,67,79,97,173,191,232,402,464,580,960,1104,
%T A240789 1400,2250,2637,3388,5280,6255,8117,12342,14819,19374,28826,35008,
%U A240789 46021,67233,82554,108956,156715,194316,257170,365065,456688,605532,850096,1071831
%N A240789 Number of n X 2 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of elements above it or zero plus the sum of the elements diagonally to its northwest or zero plus the sum of the elements antidiagonally to its northeast, modulo 4.
%H A240789 R. H. Hardin, <a href="/A240789/b240789.txt">Table of n, a(n) for n = 1..210</a>
%F A240789 Empirical: a(n) = 4*a(n-3) + a(n-5) - 3*a(n-6) - 3*a(n-8) - 4*a(n-9) + a(n-11) + 4*a(n-12) + 3*a(n-14) - 2*a(n-17) for n>19.
%F A240789 Empirical g.f.: x*(3 + 4*x + 5*x^2 - 2*x^3 - 3*x^4 - 9*x^5 - 5*x^6 - 13*x^7 - 6*x^8 - 12*x^9 + 7*x^10 + 12*x^11 + 26*x^12 + 8*x^13 - 8*x^14 - 17*x^15 - 5*x^16 + 5*x^17 + 2*x^18) / ((1 - x)*(1 + x)*(1 - x + x^2)*(1 + x + x^2)*(1 - x^2 - x^3)*(1 - 2*x^3)*(1 + x^2 - x^3 + x^4 - x^5)). - _Colin Barker_, Oct 29 2018
%e A240789 All solutions for n=4:
%e A240789 ..3..3....3..3....3..3....3..3....3..2....3..2....3..3....3..2....3..3....3..3
%e A240789 ..2..1....2..2....2..1....2..2....3..1....3..1....2..2....3..1....2..2....2..2
%e A240789 ..3..3....3..1....3..3....3..1....2..2....2..1....3..3....2..2....3..1....3..1
%e A240789 ..2..2....2..2....2..1....3..2....3..1....3..3....2..2....3..3....3..1....2..1
%Y A240789 Column 2 of A240792.
%K A240789 nonn
%O A240789 1,1
%A A240789 _R. H. Hardin_, Apr 12 2014