A239406 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, modulo 4.

5, 23, 105, 478, 2165, 9811, 44399, 201006, 909679, 4117547, 18635613, 84347726, 381758761, 1727876419, 7820451787, 35395951502, 160204196803, 725095175067, 3281826924665, 14853766696750, 67229111585533, 304283379907315

Offset: 1

Author

R. H. Hardin, Mar 17 2014

Keywords

• nonn

Examples

			Some solutions for n=5:
..3..3..1..3..0....3..1..0..0..3....0..0..3..1..3....3..3..0..0..0
..0..2..0..0..0....2..0..1..1..3....3..3..2..2..2....2..0..0..1..3
		

Links

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

Crossrefs

Row 2 of A239405.

Formula

Empirical: a(n) = 3*a(n-1) + 12*a(n-2) - 18*a(n-3) - 29*a(n-4) + 19*a(n-5) + 38*a(n-6) + 8*a(n-7).

Empirical g.f.: x*(5 + 8*x - 24*x^2 - 23*x^3 + 30*x^4 + 42*x^5 + 8*x^6) / (1 - 3*x - 12*x^2 + 18*x^3 + 29*x^4 - 19*x^5 - 38*x^6 - 8*x^7). - Colin Barker, Oct 26 2018