A241301 Number of n X 2 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of elements above it or zero 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, 6, 6, 12, 16, 28, 38, 66, 92, 154, 222, 362, 532, 854, 1272, 2018, 3036, 4776, 7236, 11316, 17230, 26832, 41000, 63658, 97516, 151086, 231858, 358688, 551144, 851718, 1309890, 2022722, 3112810, 4804190, 7396624, 11411300, 17574716, 27106414

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-2) + a(n-3) - a(n-5).

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

Example

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

Crossrefs

Column 2 of A241306.

Sequence in context: A053319 A253215 A075779 * A140880 A065420 A119312

Adjacent sequences: A241298 A241299 A241300 * A241302 A241303 A241304

Keyword

nonn

Author

R. H. Hardin, Apr 18 2014

Status

approved