A205188 Number of (n+1) X 4 0..1 arrays with the number of clockwise edge increases in every 2 X 2 subblock differing from each horizontal or vertical neighbor.

48, 64, 124, 160, 292, 384, 708, 928, 1708, 2240, 4124, 5408, 9956, 13056, 24036, 31520, 58028, 76096, 140092, 183712, 338212, 443520, 816516, 1070752, 1971244, 2585024, 4759004, 6240800, 11489252, 15066624, 27737508, 36374048, 66964268

Offset

1,1

Comments

Column 3 of A205193.

Links

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

Formula

Empirical: a(n) = 2*a(n-2) +a(n-4) for n>5.

Empirical g.f.: 4*x*(12 + 16*x + 7*x^2 + 8*x^3 - x^4) / (1 - 2*x^2 - x^4). - Colin Barker, Jun 11 2018

Example

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

Crossrefs

Cf. A205193.

Sequence in context: A114505 A323610 A186400 * A333672 A045072 A217139

Adjacent sequences: A205185 A205186 A205187 * A205189 A205190 A205191

Keyword

nonn

Author

R. H. Hardin, Jan 23 2012

Status

approved