A235947 Number of (n+1) X (1+1) 0..2 arrays colored with the upper median value of each 2 X 2 subblock.

81, 294, 905, 2584, 7353, 20800, 58896, 167240, 474948, 1344000, 3811120, 10818624, 30677136, 86900480, 246546816, 699399552, 1982514496, 5620085760, 15943384320, 45209722880, 128165455104, 363441340416, 1030800314368, 2922637780992

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-3) + 36*a(n-4) + 48*a(n-6) for n>9.

Empirical g.f.: x*(81 + 294*x + 905*x^2 + 1936*x^3 + 2085*x^4 + 2976*x^5 + 1756*x^6 + 1280*x^7 + 400*x^8) / (1 - 8*x^3 - 36*x^4 - 48*x^6). - Colin Barker, Oct 20 2018

Example

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

Crossrefs

Column 1 of A235954.

Sequence in context: A236055 A236048 A235954 * A237809 A237802 A237779

Adjacent sequences: A235944 A235945 A235946 * A235948 A235949 A235950

Keyword

nonn

Author

R. H. Hardin, Jan 17 2014

Status

approved