A236886 Number of (n+1) X (1+1) 0..2 arrays with the maximum plus the upper median minus the lower median minus the minimum of every 2 X 2 subblock equal.

81, 245, 781, 2605, 8901, 31253, 111685, 406949, 1503365, 5632837, 21327109, 81569413, 314366469, 1220142341, 4761187333, 18668554757, 73468028933, 290057876485, 1147984105477, 4553121130501, 18087737270277, 71955008016389

Offset

1,1

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 8*a(n-2) - 136*a(n-3) + 364*a(n-4) + 380*a(n-5) - 2080*a(n-6) + 992*a(n-7) + 2400*a(n-8) - 1920*a(n-9).

Empirical g.f.: x*(81 - 484*x - 776*x^2 + 8552*x^3 - 4460*x^4 - 41760*x^5 + 46992*x^6 + 46592*x^7 - 58112*x^8) / ((1 - x)*(1 - 2*x)*(1 - 4*x)*(1 - 2*x - 4*x^2)*(1 - 6*x^2)*(1 - 10*x^2)). - Colin Barker, Oct 21 2018

Example

Some solutions for n=5:
..2..0....2..1....1..1....2..2....2..0....2..2....1..2....1..2....2..1....0..1
..0..1....0..2....2..0....1..0....2..1....2..1....2..0....0..1....0..2....1..2
..0..2....1..0....0..0....2..0....0..0....1..1....0..1....1..0....1..2....1..0
..2..1....2..0....0..2....1..0....1..2....2..1....2..0....1..0....2..0....1..0
..0..2....1..2....0..0....2..2....0..0....2..2....1..0....2..1....2..1....1..2
..2..1....2..0....1..1....1..0....1..2....1..2....2..0....1..0....0..2....2..1

Crossrefs

Column 1 of A236893.

Sequence in context: A236893 A044986 A237160 * A206142 A225027 A225020

Adjacent sequences: A236883 A236884 A236885 * A236887 A236888 A236889

Keyword

nonn

Author

R. H. Hardin, Feb 01 2014

Status

approved