A260131 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 01010101 or 01010111.

36, 58, 138, 266, 472, 944, 1880, 3562, 6866, 13450, 26016, 50176, 97392, 188890, 365434, 707786, 1371848, 2657040, 5145832, 9969162, 19312130, 37406666, 72459984, 140365536, 271897664, 526684282, 1020240874, 1976299402, 3828249912

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-3) + a(n-4) for n>5.

Empirical g.f.: 2*x*(18 + 11*x + 40*x^2 + 10*x^3 - 2*x^4) / (1 - x - 3*x^3 - x^4). - Colin Barker, Dec 28 2018

Example

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

Crossrefs

Column 1 of A260138.

Sequence in context: A080469 A341283 A260138 * A320632 A368832 A188633

Adjacent sequences: A260128 A260129 A260130 * A260132 A260133 A260134

Keyword

nonn

Author

R. H. Hardin, Jul 17 2015

Status

approved