A240285 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 or zero plus the sum of the elements diagonally to its northwest, modulo 4.

2, 8, 19, 76, 181, 741, 1779, 7308, 17561, 72140, 173343, 712043, 1710905, 7027848, 16886555, 69364556, 166669597, 684625413, 1645022411, 6757226212, 16236307329, 66693560300, 160251722711, 658262849419, 1581678277825, 6497028751792

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.: x*(1 - x)*(2 + 10*x + 5*x^2 - 15*x^3 - 14*x^4 + 7*x^5 + 8*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..3..1..3....3..1..3..1....3..1..3..1....3..3..1..3
..2..1..2..0....2..0..2..3....3..1..0..0....3..2..0..0....2..0..2..2

Crossrefs

Row 2 of A240284.

Sequence in context: A026572 A074797 A248115 * A129445 A082821 A188893

Adjacent sequences: A240282 A240283 A240284 * A240286 A240287 A240288

Keyword

nonn

Author

R. H. Hardin, Apr 03 2014

Status

approved