A258918 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum equal to the antidiagonal sum or central row sum equal to the central column sum.

200, 576, 1680, 5184, 15840, 46656, 138240, 419904, 1270080, 3779136, 11275200, 34012224, 102409920, 306110016, 916090560, 2754990144, 8278407360, 24794911296, 74304112320, 223154201664, 669946334400, 2008387814976

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 6*a(n-2) + 18*a(n-3).

Empirical g.f.: 8*x*(25 - 3*x + 144*x^2) / ((1 - 3*x)*(1 + 6*x^2)). - Colin Barker, Dec 23 2018

Example

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

Crossrefs

Column 1 of A258921.

Sequence in context: A117412 A109632 A258921 * A129641 A202966 A218846

Adjacent sequences: A258915 A258916 A258917 * A258919 A258920 A258921

Keyword

nonn

Author

R. H. Hardin, Jun 14 2015

Status

approved