A251021 Number of (n+1) X (1+1) 0..3 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements.

110, 526, 1966, 6321, 18330, 49481, 126955, 314337, 759223, 1803024, 4233655, 9867700, 22890708, 52944048, 122232716, 281893771, 649688256, 1496798491, 3447701193, 7940432539, 18286472653, 42111425346, 96975351381, 223315141022

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 18*a(n-2) + 17*a(n-3) + 10*a(n-4) - 39*a(n-5) + 38*a(n-6) - 17*a(n-7) + 3*a(n-8).

Empirical g.f.: x*(110 - 244*x + 264*x^2 + 157*x^3 - 571*x^4 + 557*x^5 - 255*x^6 + 46*x^7) / ((1 - x)^6*(1 - x - 3*x^2)). - Colin Barker, Nov 24 2018

Example

Some solutions for n=4:
..0..0....1..2....0..3....0..2....1..2....0..3....1..2....1..3....0..0....0..2
..3..3....0..1....0..1....1..2....1..1....0..3....0..1....0..1....0..0....0..2
..2..0....0..0....3..3....1..1....2..0....0..3....0..1....0..0....3..0....0..2
..2..0....2..0....1..0....0..0....3..0....1..0....0..1....1..0....3..0....3..3
..2..0....3..1....3..2....2..1....3..0....1..0....1..1....3..1....3..0....0..0

Crossrefs

Column 1 of A251028.

Sequence in context: A285984 A158539 A251028 * A251030 A156852 A250536

Adjacent sequences: A251018 A251019 A251020 * A251022 A251023 A251024

Keyword

nonn

Author

R. H. Hardin, Nov 29 2014

Status

approved