A269076 Number of 2 X n binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once.

4, 11, 27, 76, 185, 489, 1204, 3059, 7539, 18748, 46001, 112977, 275620, 671387, 1629003, 3944428, 9524969, 22955577, 55208404, 132545027, 317673891, 760222300, 1816668257, 4335499425, 10333941316, 24603369515, 58513434747, 139020574348

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 5*a(n-2) - 6*a(n-3) - 9*a(n-4).

Empirical g.f.: x*(4 + 3*x - 15*x^2 - 9*x^3) / (1 - x - 3*x^2)^2. - Colin Barker, Jan 18 2019

Example

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

Crossrefs

Row 2 of A269075.

Sequence in context: A266009 A096124 A376716 * A282641 A031127 A239031

Adjacent sequences: A269073 A269074 A269075 * A269077 A269078 A269079

Keyword

nonn

Author

R. H. Hardin, Feb 19 2016

Status

approved