A279971 Number of n X 2 0..1 arrays with no element equal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

1, 3, 9, 31, 108, 366, 1205, 3873, 12207, 37859, 115842, 350412, 1049545, 3116655, 9185349, 26890375, 78253896, 226510362, 652483133, 1871302893, 5345409483, 15213423371, 43153001406, 122024489304, 344061371665, 967537410459

Offset

1,2

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 30*a(n-2) + 45*a(n-3) - 30*a(n-4) + 9*a(n-5) -a(n-6).

Empirical g.f.: x*(1 - 2*x)*(1 - 4*x + 4*x^2 + 3*x^3) / (1 - 3*x + x^2)^3. - Colin Barker, Feb 12 2019

Example

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

Crossrefs

Column 2 of A279977.

Sequence in context: A202246 A225340 A148966 * A127927 A148967 A189429

Adjacent sequences: A279968 A279969 A279970 * A279972 A279973 A279974

Keyword

nonn

Author

R. H. Hardin, Dec 24 2016

Status

approved