A240382 Number of 2 X n 0..3 arrays with no element equal to zero plus the sum of elements to its left or two plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4.

4, 10, 38, 90, 366, 878, 3606, 8666, 35602, 85550, 351418, 844394, 3468498, 8334126, 34233910, 82257450, 337887294, 811877790, 3334934438, 8013202282, 32915673442, 79089995358, 324876418346, 780615181818, 3206517628418, 7704641519326

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).

Empirical g.f.: 2*x*(1 - x)*(2 + 7*x + 2*x^2 - 13*x^3 - 10*x^4 + 9*x^5 + 10*x^6) / (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..1..3..1....3..1..3..1....1..3..1..3....1..3..1..3....3..1..3..1
..3..2..2..2....2..0..0..1....1..3..2..3....2..3..2..0....3..2..3..2

Crossrefs

Row 2 of A240381.

Sequence in context: A102755 A197551 A046562 * A220198 A197051 A149191

Adjacent sequences: A240379 A240380 A240381 * A240383 A240384 A240385

Keyword

nonn

Author

R. H. Hardin, Apr 04 2014

Status

approved