A275143 Number of 3 X n 0..2 arrays with no element equal to any value at offset (-2,-2) (-1,-2) or (0,-1) and new values introduced in order 0..2.

5, 36, 80, 224, 528, 1216, 2816, 6544, 15216, 35376, 82240, 191184, 444448, 1033216, 2401936, 5583824, 12980816, 30176736, 70152400, 163084544, 379125568, 881360016, 2048913456, 4763145904, 11072970816, 25741534096, 59841806560

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + a(n-3) for n>5.

Empirical g.f.: x*(5 + 21*x - 18*x^2 + 51*x^3 - 20*x^4) / (1 - 3*x + 2*x^2 - x^3). - Colin Barker, Feb 01 2019

Example

Some solutions for n=5:
..0..1..2..1..2. .0..1..2..1..0. .0..1..0..1..2. .0..1..2..0..2
..2..1..2..0..1. .2..1..2..0..1. .2..1..2..0..1. .2..0..2..0..1
..1..2..1..2..1. .2..0..1..0..1. .2..0..1..2..1. .0..2..1..2..1

Crossrefs

Row 3 of A275142.

Sequence in context: A003350 A344643 A217166 * A276249 A027765 A196481

Adjacent sequences: A275140 A275141 A275142 * A275144 A275145 A275146

Keyword

nonn

Author

R. H. Hardin, Jul 17 2016

Status

approved