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A204753 Number of (n+2) X 9 0..1 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically, diagonally or antidiagonally exactly three ways, and new values 0..1 introduced in row major order. 1
1051, 70, 69, 74, 82, 95, 116, 150, 205, 294, 438, 671, 1048, 1658, 2645, 4242, 6826, 11007, 17772, 28718, 46429, 75086, 121454, 196479, 317872, 514290, 832101, 1346330, 2178370, 3524639, 5702948, 9227526, 14930413, 24157878, 39088230 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 of A204754.

LINKS

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

FORMULA

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

Empirical g.f.: x*(1051 - 2032*x - 71*x^2 + 987*x^3 + 4*x^4) / ((1 - x)*(1 - x - x^2)). - Colin Barker, Jun 10 2018

EXAMPLE

Some solutions for n=3:

  0 1 1 0 1 0 0 1 0     0 1 1 1 0 0 0 1 1

  0 1 1 0 1 0 0 1 0     0 0 1 1 1 0 0 0 1

  0 1 1 0 1 0 0 1 0     0 0 0 1 1 1 0 0 0

  0 1 1 0 1 0 0 1 0     1 0 0 0 1 1 1 0 0

  0 1 1 0 1 0 0 1 0     1 1 0 0 0 1 1 1 0

CROSSREFS

Cf. A204754.

Sequence in context: A015064 A090057 A287173 * A252391 A020389 A252609

Adjacent sequences:  A204750 A204751 A204752 * A204754 A204755 A204756

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 18 2012

STATUS

approved

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Last modified September 24 22:46 EDT 2021. Contains 347651 sequences. (Running on oeis4.)