A231390 Number of (n+1) X (2+1) 0..2 arrays with no element unequal to a strict majority of its horizontal, diagonal and antidiagonal neighbors, with values 0..2 introduced in row major order.

7, 8, 15, 20, 31, 52, 95, 180, 351, 692, 1375, 2740, 5471, 10932, 21855, 43700, 87391, 174772, 349535, 699060, 1398111, 2796212, 5592415, 11184820, 22369631, 44739252, 89478495, 178956980, 357913951, 715827892, 1431655775, 2863311540, 5726623071

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(7 - 6*x - 8*x^2 - 4*x^3 - 8*x^4) / ((1 - x)*(1 + x)*(1 - 2*x)). - Colin Barker, Sep 28 2018

Example

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

Crossrefs

Column 2 of A231396.

Sequence in context: A271953 A165465 A047521 * A231458 A070424 A022097

Adjacent sequences: A231387 A231388 A231389 * A231391 A231392 A231393

Keyword

nonn

Author

R. H. Hardin, Nov 08 2013

Status

approved