A240479 Number of n X 3 0..1 arrays with no element equal to more than two horizontal or vertical neighbors, with new values 0..1 introduced in row major order.

4, 25, 122, 578, 2753, 13147, 62781, 299758, 1431221, 6833530, 32627526, 155784099, 743810095, 3551411593, 16956645850, 80961564485, 386560819918, 1845681570476, 8812430758819, 42076020653557, 200897069434265, 959207450713576

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(1 + x)*(4 + 5*x + 5*x^2 + 2*x^3 - x^4) / (1 - 4*x - 3*x^2 - 2*x^3 - 6*x^4 - 2*x^5 + x^6). - Colin Barker, Oct 29 2018

Example

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

Crossrefs

Column 3 of A240484.

Sequence in context: A260373 A362391 A175733 * A317949 A263440 A240631

Adjacent sequences: A240476 A240477 A240478 * A240480 A240481 A240482

Keyword

nonn

Author

R. H. Hardin, Apr 06 2014

Status

approved