A204368 Number of (n+2) X 8 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.

6121, 4355, 2574, 2956, 3280, 4856, 9272, 19880, 50056, 132856, 356056, 968312, 2641688, 7207448, 19686232, 53780248, 146914840, 401373080, 1096568600, 2995854104, 8184818200, 22361337112, 61092259096, 166907144984, 455998800152

Offset

1,1

Comments

Column 6 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*(6121 - 14008*x - 10491*x^2 - 4766*x^3 + 31138*x^4 + 21146*x^5 - 14336*x^6 - 7620*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..2..0..1..0..1..2....0..1..0..0..1..1..0..0....0..0..1..2..1..2..2..2
..0..1..2..0..1..0..1..2....0..1..0..0..1..1..0..0....0..0..1..2..1..2..2..1
..0..1..2..0..1..0..1..2....0..1..0..0..1..1..0..0....0..0..1..2..1..2..2..1
..0..1..2..0..1..0..1..2....0..1..0..0..1..1..0..0....0..0..1..2..1..2..2..1
..0..1..2..0..1..0..1..2....0..1..0..0..1..1..0..0....0..0..1..2..1..2..2..1
..0..1..2..0..1..0..1..2....0..0..0..0..1..1..0..0....0..0..1..2..1..2..2..1
..0..1..2..0..1..0..1..2....2..1..0..0..1..1..0..0....0..0..1..2..1..2..2..1

Crossrefs

Cf. A204370.

Sequence in context: A366516 A224483 A065695 * A114131 A144491 A184501

Adjacent sequences: A204365 A204366 A204367 * A204369 A204370 A204371

Keyword

nonn

Author

R. H. Hardin, Jan 14 2012

Status

approved