A205981 Number of (n+1) X 4 0..2 arrays with every 2 X 3 or 3 X 2 subblock having exactly two clockwise edge increases.

2232, 8004, 27060, 103998, 408411, 1599096, 6296976, 24685680, 96780240, 381085848, 1493933568, 5857190208, 23062636320, 90410256000, 354480099264, 1395709647744, 5471472881664, 21453307046400, 84465860912640

Offset

1,1

Comments

Column 3 of A205986.

Links

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

Formula

Empirical: a(n) = 60*a(n-3) +8*a(n-5) for n>9.

Empirical g.f.: 3*x*(744 + 2668*x + 9020*x^2 - 9974*x^3 - 23943*x^4 - 14120*x^5 - 2312*x^6 - 11820*x^7 + 832*x^8) / (1 - 60*x^3 - 8*x^5). - Colin Barker, Jun 13 2018

Example

Some solutions for n=4:
..0..2..0..1....0..0..0..1....2..0..2..1....1..0..2..1....0..2..2..1
..1..2..2..1....1..2..1..1....0..2..2..0....1..1..0..1....2..1..2..2
..0..1..2..2....0..1..1..2....2..2..0..2....2..1..1..2....2..2..0..1
..0..0..1..1....1..1..2..0....0..0..1..1....0..2..1..1....1..2..2..0
..1..0..1..2....1..2..0..0....2..0..1..2....1..1..2..0....2..0..2..2

Crossrefs

Cf. A205986.

Sequence in context: A252644 A205046 A205039 * A205038 A279661 A288846

Adjacent sequences: A205978 A205979 A205980 * A205982 A205983 A205984

Keyword

nonn

Author

R. H. Hardin, Feb 02 2012

Status

approved