A260920 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 00101011 or 01010101.

36, 48, 104, 186, 297, 491, 883, 1489, 2534, 4289, 7421, 12581, 21537, 36634, 62796, 106888, 182812, 311578, 532706, 908294, 1551949, 2647450, 4522307, 7716224, 13177700, 22488756, 38401007, 65541083, 111905468, 191009570, 326112380

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-5) + 2*a(n-6) + 3*a(n-7) + a(n-8) for n>10.

Empirical g.f.: x*(36 + 48*x + 68*x^2 + 138*x^3 + 85*x^4 + 89*x^5 + 106*x^6 + 28*x^7 + x^9) / (1 - x^2 - 3*x^4 - 2*x^5 - 2*x^6 - 3*x^7 - x^8). - Colin Barker, Dec 29 2018

Example

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

Crossrefs

Column 1 of A260927.

Sequence in context: A348274 A033701 A349869 * A132956 A260015 A163244

Adjacent sequences: A260917 A260918 A260919 * A260921 A260922 A260923

Keyword

nonn

Author

R. H. Hardin, Aug 04 2015

Status

approved