A240290 Number of n X 2 0..3 arrays with no element equal to zero plus the sum of elements to its left or two plus the sum of elements above it or two plus the sum of the elements diagonally to its northwest, modulo 4.

4, 6, 24, 56, 230, 552, 2270, 5456, 22416, 53864, 221258, 531640, 2183802, 5247248, 21554008, 51790104, 212737190, 511166312, 2099707822, 5045191696, 20724034720, 49795846120, 204545417674, 491483066744, 2018855326250, 4850918775632

Offset

1,1

Links

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

Formula

Empirical: a(n) = 12*a(n-2) - 24*a(n-4) + 31*a(n-6) - 16*a(n-8) for n>9.

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

Example

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

Crossrefs

Column 2 of A240295.

Sequence in context: A122174 A283185 A034458 * A067001 A057343 A343466

Adjacent sequences: A240287 A240288 A240289 * A240291 A240292 A240293

Keyword

nonn

Author

R. H. Hardin, Apr 03 2014

Status

approved