A228656 Number of nX4 binary arrays with top left value 1 and no two ones adjacent horizontally, diagonally or antidiagonally.

3, 14, 78, 416, 2228, 11912, 63688, 340480, 1820208, 9730784, 52020448, 278099456, 1486709568, 7947894912, 42489154688, 227145461760, 1214311301888, 6491663650304, 34704195603968, 185527355908096, 991822435038208

Offset

1,1

Comments

Column 4 of A228660

Links

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

Formula

Empirical: a(n) = 6*a(n-1) -2*a(n-2) -8*a(n-3).

Empirical: G.f. -x*(-3+4*x) / ( 1-6*x+2*x^2+8*x^3 ). - R. J. Mathar, Aug 29 2013

Example

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

Crossrefs

Sequence in context: A369477 A052186 A330518 * A244507 A367016 A074538

Adjacent sequences: A228653 A228654 A228655 * A228657 A228658 A228659

Keyword

nonn

Author

R. H. Hardin Aug 29 2013

Status

approved