A260009 Number of (n+2) X (2+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000101 00010101 or 01010101.

49, 98, 252, 578, 1232, 2738, 6262, 14112, 31500, 70688, 159198, 357858, 803428, 1805000, 4056988, 9116450, 20482308, 46022418, 103415312, 232373682, 522131898, 1173216800, 2636206832, 5923508168, 13309979250, 29907242450, 67201004772

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + a(n-3) + 3*a(n-4) - 5*a(n-5) - a(n-6) - a(n-8) + a(n-9) for n>10.

Empirical g.f.: x*(49 + 56*x^2 + 25*x^3 - 169*x^4 - 27*x^5 - 9*x^6 - 20*x^7 + 33*x^8 - x^9) / ((1 - 2*x - x^2 + x^3)*(1 + x^2 - 2*x^4 - x^6)). - Colin Barker, Dec 27 2018

Example

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

Crossrefs

Column 2 of A260015.

Sequence in context: A043394 A044519 A031484 * A114013 A235578 A161689

Adjacent sequences: A260006 A260007 A260008 * A260010 A260011 A260012

Keyword

nonn

Author

R. H. Hardin, Jul 13 2015

Status

approved