A184489 Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock sum greater than 4.

31, 165, 792, 3971, 19593, 97312, 482071, 2390621, 11850280, 58751643, 291260673, 1443961520, 7158542031, 35489140405, 175940409400, 872240066291, 4324205636281, 21437626315584, 106278895767879, 526886873434445

Offset

1,1

Comments

Column 1 of A184497.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 3*a(n-1) + 11*a(n-2) - 4*a(n-3) - 12*a(n-4).

Empirical g.f.: x*(31 + 72*x - 44*x^2 - 96*x^3) / ((1 + 2*x)*(1 - 5*x - x^2 + 6*x^3)). - Colin Barker, Apr 12 2018

Example

Some solutions for 3 X 2:
..2..0....1..2....2..1....2..1....2..1....1..0....2..2....1..2....1..2....2..2
..2..1....1..1....2..2....2..2....1..1....2..2....2..2....2..2....2..2....1..2
..2..1....2..1....0..2....1..0....1..2....2..1....1..0....1..2....2..0....2..2

Crossrefs

Cf. A184497.

Sequence in context: A142306 A296114 A184497 * A140540 A183877 A107953

Adjacent sequences: A184486 A184487 A184488 * A184490 A184491 A184492

Keyword

nonn

Author

R. H. Hardin, Jan 15 2011

Status

approved