A235883 Number of (n+1) X (7+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.

7329, 8871, 11973, 18231, 30909, 56751, 109893, 220551, 454989, 963231, 2097813, 4721271, 11031069, 26839311, 68021733, 179084391, 487303149, 1362020991, 3886297653, 11259373911, 32979095229, 97339244271, 288821661573

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*(2443 - 11701*x + 13122*x^2) / ((1 - x)*(1 - 2*x)*(1 - 3*x)).

a(n) = 3*(1932 + 127*2^(1+n) + 3^n).

(End)

Example

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

Crossrefs

Column 7 of A235884.

Sequence in context: A328786 A295004 A202167 * A117799 A295003 A097696

Adjacent sequences: A235880 A235881 A235882 * A235884 A235885 A235886

Keyword

nonn

Author

R. H. Hardin, Jan 16 2014

Status

approved