A241256 Number of 2 X n 0..3 arrays with no element equal to one plus the sum of elements to its left or zero plus the sum of the elements above it or one plus the sum of the elements diagonally to its northwest or zero plus the sum of the elements antidiagonally to its northeast, modulo 4.

2, 5, 4, 10, 12, 22, 41, 59, 120, 171, 306, 494, 784, 1345, 2112, 3547, 5782, 9402, 15643, 25307, 41868, 68465, 112078, 184535, 301346, 495580, 811726, 1330658, 2184497, 3577622, 5872217, 9625155, 15783147, 25889388, 42437724, 69611469, 114132047

Offset: 1

Author

R. H. Hardin, Apr 18 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Row 2 of A241255.

Formula

Empirical: a(n) = 2*a(n-2) + 2*a(n-3) - a(n-4) - a(n-5) - a(n-6) + a(n-7) + 2*a(n-8) + a(n-10) for n>12.

Empirical g.f.: x*(2 + 5*x - 4*x^3 - 4*x^4 + x^5 + 8*x^6 + 8*x^7 + 11*x^8 + x^9 + 3*x^10 - 3*x^11) / ((1 + x)*(1 - x - x^2 - x^3 + 2*x^4 - x^5 + 2*x^6 - 3*x^7 + x^8 - x^9)). - Colin Barker, Oct 29 2018