A204485 Number of (n+2) X 3 0..1 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly one way, and new values 0..1 introduced in row major order.

72, 214, 610, 1690, 4664, 12809, 35172, 96615, 265372, 728983, 2002395, 5500247, 15108294, 41499921, 113994101, 313124795, 860106901, 2362586936, 6489676798, 17826180446, 48965883404, 134502048011, 369457236654, 1014844430800

Offset

1,1

Comments

Column 1 of A204492.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -a(n-2) +4*a(n-3) -10*a(n-4) +18*a(n-6) -23*a(n-7) -3*a(n-9) +43*a(n-10) -86*a(n-11) +114*a(n-12) -85*a(n-13) +46*a(n-14) -16*a(n-15) -3*a(n-16) -4*a(n-17) +4*a(n-18) for n>19.

Example

Some solutions for n=3
..0..0..0....0..1..0....0..0..1....0..0..1....0..1..1....0..0..1....0..1..0
..0..1..1....0..0..1....0..1..0....1..1..0....0..1..0....0..1..0....1..1..1
..1..0..0....1..1..1....0..1..1....0..0..0....1..1..0....1..1..1....0..0..1
..0..1..0....0..1..0....1..1..0....0..1..1....0..1..1....0..0..1....1..0..0
..0..1..0....1..0..0....0..1..1....1..1..0....1..1..0....0..1..0....0..0..1

Crossrefs

Cf. A204492.

Sequence in context: A235186 A235179 A204492 * A358514 A344179 A050498

Adjacent sequences: A204482 A204483 A204484 * A204486 A204487 A204488

Keyword

nonn

Author

R. H. Hardin, Jan 15 2012

Status

approved