A251145 Number of (n+1) X (4+1) 0..2 arrays with every 2 X 2 subblock summing to 4 and no 2 X 2 subblock having exactly two nonzero entries.

107, 161, 247, 401, 667, 1141, 1987, 3521, 6327, 11521, 21227, 39541, 74387, 141201, 270167, 520561, 1009147, 1966581, 3849507, 7563681, 14908407, 29462561, 58351947, 115776501, 230052467, 457677041, 911425687, 1816495121, 3622705627

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 5*a(n-3) + a(n-4) + 2*a(n-5).

Empirical g.f.: x*(107 - 160*x - 236*x^2 + 195*x^3 + 162*x^4) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 - x - x^2)). - Colin Barker, Nov 26 2018

Example

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

Crossrefs

Column 4 of A251149.

Sequence in context: A039555 A376500 A161403 * A168475 A142662 A178416

Adjacent sequences: A251142 A251143 A251144 * A251146 A251147 A251148

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved