A261106 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010001 00010101 or 01010101.

28, 33, 63, 97, 183, 289, 547, 865, 1639, 2593, 4915, 7777, 14743, 23329, 44227, 69985, 132679, 209953, 398035, 629857, 1194103, 1889569, 3582307, 5668705, 10746919, 17006113, 32240755, 51018337, 96722263, 153055009, 290166787, 459165025

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(28 + 5*x - 54*x^2 + 19*x^3 - 4*x^4 + 4*x^5) / ((1 - x)*(1 - 3*x^2)). - Colin Barker, Dec 30 2018

Example

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

Crossrefs

Column 1 of A261113.

Sequence in context: A261113 A280649 A134657 * A138687 A330758 A214470

Adjacent sequences: A261103 A261104 A261105 * A261107 A261108 A261109

Keyword

nonn

Author

R. H. Hardin, Aug 08 2015

Status

approved