A252224 Number of (n+2) X (4+2) 0..2 arrays with every 3 X 3 subblock row and column sum 2 3 or 4 and every diagonal and antidiagonal sum not 2 3 or 4.

1442, 7724, 24932, 58334, 160688, 512822, 1619714, 4972874, 15236172, 46914228, 144610766, 445412672, 1371485862, 4223410850, 13006666602, 40055759564, 123355278788, 379883410622, 1169887334864, 3602781631574, 11095111201922

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - a(n-2) + 3*a(n-3) + 3*a(n-4) - a(n-5) - a(n-6) for n>8.

Empirical g.f.: 2*x*(721 + 1699*x + 1601*x^2 - 6532*x^3 - 8440*x^4 - 3717*x^5 + 652*x^6 + 1072*x^7) / ((1 - x + 2*x^2 - x^3)*(1 - 2*x - 3*x^2 - x^3)). - Colin Barker, Dec 02 2018

Example

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

Crossrefs

Column 4 of A252228.

Sequence in context: A362863 A178275 A220651 * A221872 A251842 A105417

Adjacent sequences: A252221 A252222 A252223 * A252225 A252226 A252227

Keyword

nonn

Author

R. H. Hardin, Dec 15 2014

Status

approved