A259735 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 or 01010101.

20, 22, 42, 62, 101, 152, 265, 382, 652, 962, 1649, 2412, 4135, 6062, 10386, 15222, 26089, 38232, 65517, 96022, 164556, 241162, 413285, 605692, 1037987, 1521222, 2606954, 3820622, 6547485, 9595672, 16444321, 24099982, 41300684, 60528242

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-2) + 3*a(n-4) + 2*a(n-6) for n>7.

Empirical g.f.: x*(20 + 22*x + 22*x^2 + 40*x^3 - x^4 + 24*x^5 - 2*x^6) / (1 - x^2 - 3*x^4 - 2*x^6). - Colin Barker, Dec 26 2018

Example

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

Crossrefs

Column 1 of A259742.

Sequence in context: A171953 A133260 A163630 * A033906 A367620 A322323

Adjacent sequences: A259732 A259733 A259734 * A259736 A259737 A259738

Keyword

nonn

Author

R. H. Hardin, Jul 04 2015

Status

approved