A235882 Number of (n+1) X (6+1) 0..2 arrays with the minimum plus the upper median equal to the lower median plus the maximum in every 2 X 2 subblock.

2571, 3345, 4911, 8097, 14631, 28185, 56751, 118257, 254391, 566025, 1307391, 3144417, 7881351, 20543865, 55434831, 153914577, 436967511, 1261353705, 3684967071, 10856716737, 32173784871, 95728627545, 285600432111

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3).

Conjectures from Colin Barker, Oct 19 2018: (Start)

G.f.: 3*x*(857 - 4027*x + 4374*x^2) / ((1 - x)*(1 - 2*x)*(1 - 3*x)).

a(n) = 3*(602 + 63*2^(1+n) + 3^n).

(End)

Example

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

Crossrefs

Column 6 of A235884.

Sequence in context: A170794 A068265 A252677 * A156627 A175016 A260104

Adjacent sequences: A235879 A235880 A235881 * A235883 A235884 A235885

Keyword

nonn

Author

R. H. Hardin, Jan 16 2014

Status

approved