A240428 - OEIS

%I #10 Oct 27 2018 12:51:46

%S 2,6,24,58,236,566,2322,5578,22912,55054,226148,543394,2232094,

%T 5363294,22030696,52935498,217442092,522471270,2146144946,5156771098,

%U 21182367216,50897130430,209069141604,502352700210,2063504305918,4958201635918

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

%H R. H. Hardin, <a href="/A240428/b240428.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 12*a(n-2) - 24*a(n-4) + 31*a(n-6) - 16*a(n-8).

%F Empirical g.f.: 2*x*(1 - x)*(1 + 4*x + 4*x^2 - 3*x^3 - 5*x^4 + 2*x^5 + 4*x^6) / (1 - 12*x^2 + 24*x^4 - 31*x^6 + 16*x^8). - _Colin Barker_, Oct 27 2018

%e Some solutions for n=4:

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

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

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

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

%Y Column 2 of A240433.

%K nonn

%O 1,1

%A _R. H. Hardin_, Apr 04 2014