A239643 - OEIS

%I #6 Jun 02 2025 09:30:18

%S 4,20,112,560,2874,14788,75540,387306,1983686,10160422,52047250,

%T 266599168,1365605466,6995075202,35830971136,183537592492,

%U 940137864960,4815683846868,24667460086554,126354551389040,647228071957412

%N Number of nX2 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, modulo 4.

%C Column 2 of A239649

%H R. H. Hardin, <a href="/A239643/b239643.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) +16*a(n-2) +31*a(n-3) -8*a(n-4) -78*a(n-5) -45*a(n-6) +56*a(n-7) -32*a(n-8) +32*a(n-9) +16*a(n-10)

%e Some solutions for n=5

%e ..1..0....1..3....3..1....3..1....1..0....1..0....1..0....1..0....3..1....1..0

%e ..1..3....2..0....3..2....3..2....2..0....2..1....2..1....2..0....3..2....1..0

%e ..2..0....3..2....3..2....2..0....3..0....3..0....3..0....3..1....1..2....1..3

%e ..1..0....2..0....1..0....1..3....3..0....2..1....2..1....3..0....3..0....3..2

%e ..2..0....3..0....3..0....1..2....2..0....3..1....1..2....1..2....2..0....2..0

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 23 2014