A261259 Number of (n+2) X (2+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 00100101 or 01010101.

41, 52, 110, 232, 418, 758, 1436, 2724, 5122, 9588, 17988, 33828, 63574, 119382, 224202, 421154, 791148, 1486082, 2791356, 5243210, 9848830, 18499920, 34749860, 65273442, 122608532, 230305832, 432602416, 812592642, 1526359722, 2867087450

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-1) + 2*a(n-3) + a(n-4) + 2*a(n-5) for n>6.

Empirical g.f.: x*(41 + 11*x + 58*x^2 + 40*x^3 + 41*x^4 - 14*x^5) / (1 - x - 2*x^3 - x^4 - 2*x^5). - Colin Barker, Dec 30 2018

Example

Some solutions for n=4:
..0..0..1..0....0..0..1..0....0..0..1..0....0..1..0..1....0..1..0..1
..1..0..0..1....0..0..0..1....0..1..0..1....0..0..1..0....1..0..1..0
..0..0..1..0....1..0..1..0....1..0..1..0....0..1..0..0....0..1..0..0
..0..1..0..1....0..1..0..1....0..1..0..1....1..0..1..0....1..0..1..0
..1..0..1..0....0..0..1..0....1..0..0..0....0..1..0..1....0..1..0..1
..0..1..0..1....1..0..0..1....0..1..0..0....1..0..0..0....1..0..0..0

Crossrefs

Column 2 of A261265.

Sequence in context: A124967 A224443 A349779 * A168348 A052032 A176924

Adjacent sequences: A261256 A261257 A261258 * A261260 A261261 A261262

Keyword

nonn

Author

R. H. Hardin, Aug 13 2015

Status

approved