A261258 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 00100101 or 01010101.

36, 41, 91, 166, 321, 586, 1123, 2082, 3938, 7358, 13863, 25971, 48833, 91602, 172099, 323001, 606629, 1138805, 2138465, 4014874, 7538696, 14154181, 26576436, 49899170, 93691463, 175913869, 330296900, 620163290, 1164419552, 2186309750

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-1) + a(n-2) + 2*a(n-4) + a(n-6) for n>7.

Empirical g.f.: x*(36 + 5*x + 14*x^2 + 34*x^3 - 8*x^4 + 17*x^5 - 2*x^6) / (1 - x - x^2 - 2*x^4 - x^6). - Colin Barker, Dec 30 2018

Example

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

Crossrefs

Column 1 of A261265.

Sequence in context: A225103 A067372 A084147 * A261372 A044862 A162526

Adjacent sequences: A261255 A261256 A261257 * A261259 A261260 A261261

Keyword

nonn

Author

R. H. Hardin, Aug 13 2015

Status

approved