A184449 1/36 the number of (n+2) X 3 0..2 arrays with each 3 X 3 subblock containing two of one value, two of another, and five of the last.

63, 234, 864, 3159, 12879, 51759, 203391, 898857, 3877551, 16120377, 75287475, 340653681, 1468371483, 7083577089, 32959439379, 145024403049, 711949718619, 3363197265009, 14961791864691, 74118576012057, 352900936009611

Offset

1,1

Comments

Column 1 of A184457.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 3*a(n-1) + 162*a(n-3) - 486*a(n-4) - 5832*a(n-6) + 17496*a(n-7).

Empirical g.f.: 9*x*(7 + 5*x + 18*x^2 - 1071*x^3 - 432*x^4 - 1458*x^5 + 35964*x^6) / ((1 - 3*x)*(1 - 54*x^3)*(1 - 108*x^3)). - Colin Barker, Apr 12 2018

Example

Some solutions with a(1,1)=0 for 4 X 3:
..0..2..0....0..1..2....0..1..1....0..1..2....0..1..0....0..0..0....0..0..0
..0..0..1....1..0..1....1..2..0....1..0..1....1..0..2....2..2..0....1..1..2
..0..2..1....1..1..2....1..1..2....1..1..2....0..0..2....0..1..1....0..2..0
..0..0..2....1..2..0....0..1..1....2..0..1....0..0..1....0..0..0....2..2..2

Crossrefs

Cf. A184457.

Sequence in context: A083079 A230651 A184457 * A158676 A157948 A326388

Adjacent sequences: A184446 A184447 A184448 * A184450 A184451 A184452

Keyword

nonn

Author

R. H. Hardin, Jan 14 2011

Status

approved