Voozh

A239594

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 one plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4.

4, 3, 4, 4, 5, 7, 8, 11, 12, 16, 19, 24, 30, 36, 46, 55, 70, 85, 106, 131, 161, 201, 246, 307, 377, 468, 578, 714, 885, 1091, 1353, 1669, 2067, 2554, 3158, 3907, 4827, 5974, 7381, 9132, 11288, 13959, 17262, 21340, 26394, 32628, 40353, 49890, 61693, 76284, 94321

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = a(n-2) + a(n-5) for n>6.

Empirical g.f.: x*(4 + 3*x + x^3 + x^4 - x^5) / (1 - x^2 - x^5). - Colin Barker, Oct 26 2018

EXAMPLE

All solutions for n=4:

..2..0....2..0....3..0....2..0

..2..0....2..0....2..3....2..0