A235890 Number of (n+1) X (5+1) 0..3 arrays with the minimum plus the upper median equal to the lower median plus the maximum in every 2 X 2 subblock.

4480, 5272, 6952, 10696, 19720, 43912, 116872, 361096, 1242760, 4578952, 17542792, 68636296, 271486600, 1079840392, 4307160712, 17204252296, 68768239240, 274975428232, 1099706666632, 4398436585096, 17592966188680, 70370304462472

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 14*a(n-2) + 8*a(n-3).

Conjectures from Colin Barker, Oct 20 2018: (Start)

G.f.: 8*x*(560 - 3261*x + 4096*x^2) / ((1 - x)*(1 - 2*x)*(1 - 4*x)).

a(n) = 4*(930 + 93*2^n + 4^n).

(End)

Example

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

Crossrefs

Column 5 of A235893.

Sequence in context: A221007 A203938 A345181 * A237775 A179161 A139068

Adjacent sequences: A235887 A235888 A235889 * A235891 A235892 A235893

Keyword

nonn

Author

R. H. Hardin, Jan 16 2014

Status

approved