A251012 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements less than the maximum of its antidiagonal elements.

63, 423, 2828, 18910, 126468, 845838, 5657125, 37835923, 253053775, 1692471213, 11319565544, 75707381676, 506345196624, 3386531834524, 22649761354057, 151485860598125, 1013165905036839, 6776243981293283, 45320793234098820

Offset

1,1

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 18*a(n-2) + 18*a(n-3) - 7*a(n-4) + a(n-5).

Empirical g.f.: x*(63 - 144*x + 155*x^2 - 62*x^3 + 9*x^4) / (1 - 9*x + 18*x^2 - 18*x^3 + 7*x^4 - x^5). - Colin Barker, Nov 24 2018

Example

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

Crossrefs

Column 1 of A251019.

Sequence in context: A068022 A131993 A251019 * A092050 A055817 A075934

Adjacent sequences: A251009 A251010 A251011 * A251013 A251014 A251015

Keyword

nonn

Author

R. H. Hardin, Nov 29 2014

Status

approved