A253464 Number of (n+1) X (3+1) 0..2 arrays with every 2 X 2 subblock diagonal maximum minus antidiagonal minimum unequal to its neighbors horizontally, vertically, diagonally and antidiagonally.

3640, 1400, 2000, 2600, 5000, 7784, 17000, 28520, 65000, 111464, 257000, 443240, 1025000, 1770344, 4097000, 7078760, 16385000, 28312424, 65537000, 113247080, 262145000, 452985704, 1048577000, 1811940200, 4194305000, 7247758184

Offset

1,1

Links

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

Formula

Empirical: a(n) = 5*a(n-2) - 4*a(n-4) for n>6.

Empirical g.f.: 8*x*(455 + 175*x - 2025*x^2 - 550*x^3 + 1195*x^4 + 48*x^5) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 + 2*x)). - Colin Barker, Dec 14 2018

Example

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

Crossrefs

Column 3 of A253468.

Sequence in context: A253498 A253491 A253452 * A015294 A186870 A185613

Adjacent sequences: A253461 A253462 A253463 * A253465 A253466 A253467

Keyword

nonn

Author

R. H. Hardin, Jan 01 2015

Status

approved