A240285 Number of 2 X n 0..3 arrays with no element equal to one plus the sum of elements to its left or two plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4.

2, 8, 19, 76, 181, 741, 1779, 7308, 17561, 72140, 173343, 712043, 1710905, 7027848, 16886555, 69364556, 166669597, 684625413, 1645022411, 6757226212, 16236307329, 66693560300, 160251722711, 658262849419, 1581678277825, 6497028751792

Offset: 1

Author

R. H. Hardin, Apr 03 2014

Keywords

• nonn

Examples

			Some solutions for n=4:
..3..1..3..1....3..3..1..3....3..1..3..1....3..1..3..1....3..3..1..3
..2..1..2..0....2..0..2..3....3..1..0..0....3..2..0..0....2..0..2..2
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Row 2 of A240284.

Formula

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

Empirical g.f.: x*(1 - x)*(2 + 10*x + 5*x^2 - 15*x^3 - 14*x^4 + 7*x^5 + 8*x^6) / (1 - 12*x^2 + 24*x^4 - 31*x^6 + 16*x^8). - Colin Barker, Oct 27 2018