A204379 Number of (n+2) X 8 0..1 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly three ways, and new values 0..1 introduced in row major order.

286, 128, 139, 153, 176, 217, 283, 388, 559, 837, 1284, 2009, 3183, 5080, 8151, 13121, 21160, 34169, 55219, 89276, 144383, 233549, 377820, 611257, 988967, 1600112, 2588967, 4188969, 6777824, 10966681, 17744395, 28710964, 46455247, 75166101

Offset

1,1

Comments

Column 6 of A204381.

Links

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

Formula

Empirical: a(n) = a(n-1) +a(n-2) +a(n-3) -a(n-4) -a(n-5) for n>8.

Empirical g.f.: x*(286 - 158*x - 275*x^2 - 400*x^3 + 42*x^4 + 163*x^5 + 4*x^6 + 4*x^7) / ((1 - x)*(1 - x - x^2)*(1 + x + x^2)). - Colin Barker, Jun 07 2018

Example

Some solutions for n=3:
..0..0..0..0..0..0..0..1....0..1..1..1..0..0..0..1....0..0..0..0..0..0..0..1
..1..1..1..1..1..1..1..1....0..0..1..1..1..0..0..0....1..1..1..1..1..1..1..1
..1..1..1..1..1..1..1..1....0..0..0..1..1..1..0..0....1..1..1..1..1..1..1..1
..0..0..0..0..0..0..0..0....1..0..0..0..1..1..1..0....0..0..0..0..0..0..0..0
..1..1..1..1..1..1..1..1....0..1..0..0..0..1..1..1....0..0..0..0..0..0..0..0

Crossrefs

Cf. A204381.

Sequence in context: A146893 A353544 A090089 * A025384 A256000 A253329

Adjacent sequences: A204376 A204377 A204378 * A204380 A204381 A204382

Keyword

nonn

Author

R. H. Hardin, Jan 14 2012

Status

approved