A222684 Number of nX2 0..2 arrays with exactly floor(nX2/2) elements unequal to at least one horizontal or antidiagonal neighbor, with new values introduced in row major 0..2 order

0, 3, 8, 50, 216, 1120, 5440, 27576, 138560, 704880, 3590400, 18382208, 94348800, 485706240, 2505943040, 12956458880, 67108497408, 348156924160, 1808830924800, 9409953735168, 49010429163520, 255537995550720, 1333668320575488

Offset

1,2

Comments

Column 2 of A222690

Links

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

Formula

From Vaclav Kotesovec, May 23 2013: (Start)

Empirical: 3*(n-1)*n*(49*n-73)*a(n) = 5*(n-1)*(98*n^2-195*n+91)*a(n-1) + 5*(7*n-5)*(49*n^2-136*n+96)*a(n-2) - 8*(n-1)*(2*n-5)*(49*n-24)*a(n-3)

a(n) ~ 16^n/(3^n*sqrt(21*Pi*n)). (End)

Example

All solutions for n=3
..0..0....0..0....0..0....0..0....0..0....0..1....0..0....0..1
..1..2....0..0....1..0....0..0....0..1....2..2....0..1....0..0
..2..2....1..2....0..0....1..0....0..0....2..2....2..2....0..0

Crossrefs

Sequence in context: A194364 A338439 A005444 * A208801 A019044 A265961

Adjacent sequences: A222681 A222682 A222683 * A222685 A222686 A222687

Keyword

nonn

Author

R. H. Hardin Feb 28 2013

Status

approved