A251146 Number of (n+1) X (5+1) 0..2 arrays with every 2 X 2 subblock summing to 4 and no 2 X 2 subblock having exactly two nonzero entries.

213, 299, 433, 667, 1061, 1743, 2925, 5003, 8689, 15307, 27317, 49359, 90237, 166811, 311569, 587515, 1117445, 2141775, 4132941, 8022251, 15650353, 30663019, 60294293, 118919247, 235137501, 465904763, 924738385, 1838035483, 3657558629

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*(213 - 340*x - 464*x^2 + 433*x^3 + 342*x^4) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 - x - x^2)). - Colin Barker, Nov 26 2018

Example

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

Crossrefs

Column 5 of A251149.

Sequence in context: A252032 A252025 A238019 * A085309 A252024 A302256

Adjacent sequences: A251143 A251144 A251145 * A251147 A251148 A251149

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved