A251148 Number of (n+1) X (7+1) 0..2 arrays with every 2 X 2 subblock summing to 4 and no 2 X 2 subblock having exactly two nonzero entries.

853, 1075, 1413, 1987, 2925, 4491, 7101, 11491, 18917, 31587, 53389, 91275, 157789, 275843, 487717, 872259, 1577901, 2886539, 5337725, 9971363, 18803813, 35765155, 68549453, 132276107, 256749085, 500872771, 981317541, 1929582211, 3805684077

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*(853 - 1484*x - 1812*x^2 + 2013*x^3 + 1486*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..0..1..1..1..1..2..1....2..0..2..0..1..0..1..1....0..1..1..0..1..2..1..1
..2..1..2..0..2..0..1..0....1..1..1..1..2..1..2..0....2..1..1..2..1..0..1..1
..1..0..1..1..1..1..2..1....2..0..2..0..1..0..1..1....0..1..1..0..1..2..1..1
..1..2..1..1..1..1..0..1....1..1..1..1..2..1..2..0....2..1..1..2..1..0..1..1
..1..0..1..1..1..1..2..1....2..0..2..0..1..0..1..1....0..1..1..0..1..2..1..1

Crossrefs

Column 7 of A251149.

Sequence in context: A237763 A237760 A234539 * A127593 A248856 A251050

Adjacent sequences: A251145 A251146 A251147 * A251149 A251150 A251151

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved