cp's OEIS Frontend

A240047 Number of 2Xn 0..3 arrays with no element equal to zero 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.

%I A240047 #6 Jun 02 2025 09:39:28
%S A240047 2,4,9,20,33,76,117,232,398,675,1228,2002,3548,5935,10128,17287,28967,
%T A240047 49649,83130,141412,238567,402406,681948,1147552,1943230,3275448,
%U A240047 5532679,9343794,15759620,26629572,44915334,75854561,128021118,216075045
%N A240047 Number of 2Xn 0..3 arrays with no element equal to zero 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.
%C A240047 Row 2 of A240046
%H A240047 R. H. Hardin, <a href="/A240047/b240047.txt">Table of n, a(n) for n = 1..210</a>
%F A240047 Empirical: a(n) = 3*a(n-2) +4*a(n-3) -3*a(n-4) -7*a(n-5) -5*a(n-6) +6*a(n-7) +4*a(n-8) +a(n-9) -3*a(n-10) +2*a(n-11) -a(n-12) -2*a(n-14) +4*a(n-15) -2*a(n-18) for n>22
%e A240047 Some solutions for n=3
%e A240047 ..3..2..2....3..2..2....3..2..2....2..3..2....3..2..2....3..2..2....3..2..3
%e A240047 ..1..0..0....2..0..3....2..1..0....3..0..0....1..0..3....2..0..0....2..1..0
%K A240047 nonn
%O A240047 1,1
%A A240047 _R. H. Hardin_, Mar 31 2014