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.

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

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