A235850 Number of (n+1) X (1+1) 0..3 arrays with the upper median equal to the lower median in every 2 X 2 subblock.

100, 688, 4524, 30624, 203804, 1370656, 9159084, 61448672, 411235964, 2756437664, 18457746444, 123673955168, 828338389340, 5549386326048, 37171828238188, 249015367157984, 1668057104261948, 11174114559613344, 74852144107435468

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 37*a(n-2) - 10*a(n-3) - 200*a(n-4) + 128*a(n-5).

Empirical g.f.: 4*x*(25 + 122*x - 138*x^2 - 720*x^3 + 512*x^4) / (1 - 2*x - 37*x^2 + 10*x^3 + 200*x^4 - 128*x^5). - Colin Barker, Oct 19 2018

Example

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

Crossrefs

Column 1 of A235856.

Sequence in context: A250707 A250708 A235856 * A264539 A233635 A233628

Adjacent sequences: A235847 A235848 A235849 * A235851 A235852 A235853

Keyword

nonn

Author

R. H. Hardin, Jan 16 2014

Status

approved