A204369 Number of (n+2) X 9 0..2 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..2 introduced in row major order.

13693, 11671, 6786, 6772, 7376, 9272, 12896, 24064, 54880, 136096, 360416, 973952, 2644160, 7212160, 19693504, 53781184, 146920256, 401383616, 1096566464, 2995860928, 8184835264, 22361328832, 61092268736, 166907175104, 455998779584

Offset

1,1

Comments

Column 7 of A204370.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -6*a(n-4) +4*a(n-6) for n>9.

Empirical g.f.: x*(13693 - 29408*x - 28227*x^2 - 13586*x^3 + 69218*x^4 + 57170*x^5 - 28976*x^6 - 20676*x^7 - 200*x^8) / ((1 - x)*(1 - 2*x - 2*x^2)*(1 - 2*x^3)). - Colin Barker, Jun 07 2018

Example

Some solutions for n=5:
..0..1..0..0..1..2..0..1..1....0..1..2..0..1..0..2..1..0
..0..1..0..0..1..2..0..1..1....0..1..2..0..1..0..2..1..0
..0..1..0..0..1..2..0..1..1....0..1..2..0..1..0..2..1..0
..0..1..0..0..1..2..0..1..1....0..1..2..0..1..0..2..1..0
..0..1..0..0..1..2..0..1..1....0..1..2..0..1..0..2..1..0
..0..1..0..0..1..2..0..1..1....0..1..2..0..1..0..2..1..0
..0..1..0..0..1..2..0..1..1....0..1..2..0..1..0..2..1..0

Crossrefs

Cf. A204370.

Sequence in context: A203727 A088870 A047827 * A226020 A157669 A236052

Adjacent sequences: A204366 A204367 A204368 * A204370 A204371 A204372

Keyword

nonn

Author

R. H. Hardin, Jan 14 2012

Status

approved