A235949 Number of (n+1) X (3+1) 0..2 arrays colored with the upper median value of each 2 X 2 subblock.

905, 1372, 1494, 1780, 2478, 3504, 4884, 6888, 9816, 13920, 19554, 27600, 39296, 55680, 78216, 110400, 157184, 222720, 312864, 441600, 628736, 890880, 1251456, 1766400, 2514944, 3563520, 5005824, 7065600, 10059776, 14254080, 20023296

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-4) for n>13.

Empirical g.f.: x*(905 + 1372*x + 1494*x^2 + 1780*x^3 - 1142*x^4 - 1984*x^5 - 1092*x^6 - 232*x^7 - 96*x^8 - 96*x^9 + 18*x^10 + 48*x^11 + 32*x^12) / ((1 - 2*x^2)*(1 + 2*x^2)). - Colin Barker, Oct 20 2018

Example

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

Crossrefs

Column 3 of A235954.

Sequence in context: A249706 A098237 A068856 * A330284 A330303 A181257

Adjacent sequences: A235946 A235947 A235948 * A235950 A235951 A235952

Keyword

nonn

Author

R. H. Hardin, Jan 17 2014

Status

approved