A241371 Number of 2 X n 0..2 arrays with no element equal to fewer vertical neighbors than horizontal neighbors, with new values 0..2 introduced in row major order.

2, 7, 28, 121, 523, 2261, 9775, 42261, 182711, 789933, 3415199, 14765285, 63836295, 275990109, 1193216815, 5158758677, 22303399319, 96426611981, 416891226559, 1802389311557, 7792457656743, 33689944754365, 145655251212111

Offset

1,1

Links

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

Formula

Empirical: a(n) = 5*a(n-1) - 2*a(n-2) - 4*a(n-3) for n>5.

Empirical g.f.: x*(1 - x - x^2)*(2 - x - 2*x^2) / (1 - 5*x + 2*x^2 + 4*x^3). - Colin Barker, Oct 30 2018

Example

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

Crossrefs

Row 2 of A241370.

Sequence in context: A150657 A150658 A026770 * A368970 A010683 A276852

Adjacent sequences: A241368 A241369 A241370 * A241372 A241373 A241374

Keyword

nonn

Author

R. H. Hardin, Apr 20 2014

Status

approved