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A204375 Number of (n+2) X 4 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. 1
51, 48, 54, 63, 88, 128, 193, 300, 470, 747, 1196, 1920, 3093, 4992, 8062, 13031, 21072, 34080, 55129, 89188, 144294, 233459, 377732, 611168, 988877, 1600024, 2588878, 4188879, 6777736, 10966592, 17744305, 28710876, 46455158, 75166011, 121621148 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 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*(51 - 3*x - 45*x^2 - 90*x^3 - 26*x^4 + 22*x^5 + 16*x^6 + 8*x^7) / ((1 - x)*(1 - x - x^2)*(1 + x + x^2)). - Colin Barker, Jun 07 2018

EXAMPLE

Some solutions for n=3:

..0..1..1..1....0..0..0..0....0..0..0..1....0..0..1..0....0..0..0..1

..0..0..1..1....0..0..0..0....1..1..0..1....0..0..1..0....1..1..1..1

..0..0..0..1....1..1..1..1....0..0..0..0....0..0..1..0....1..1..1..1

..1..0..0..0....0..0..0..0....0..0..0..0....0..0..1..0....0..0..0..0

..0..1..0..0....0..0..0..0....1..1..1..1....0..0..1..0....1..1..1..1

CROSSREFS

Cf. A204381.

Sequence in context: A191514 A334339 A131536 * A003912 A039932 A210183

Adjacent sequences:  A204372 A204373 A204374 * A204376 A204377 A204378

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 14 2012

STATUS

approved

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Last modified September 25 05:14 EDT 2021. Contains 347652 sequences. (Running on oeis4.)