A252271 Number of (n+2) X (1+2) 0..3 arrays with every 3 X 3 subblock row and column sum not equal to 2 3 4 6 or 7 and every 3 X 3 diagonal and antidiagonal sum equal to 2 3 4 6 or 7.

206, 185, 232, 322, 535, 852, 1260, 2221, 3676, 5538, 9911, 16558, 25052, 44989, 75320, 114066, 204999, 343366, 520108, 934893, 1566072, 2372290, 4264343, 7143510, 10821116, 19451805, 32585288, 49360882, 88730215, 148639302

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-3) - 7*a(n-6) + 2*a(n-9) for n>12.

Empirical g.f.: x*(206 + 185*x + 232*x^2 - 914*x^3 - 575*x^4 - 540*x^5 + 770*x^6 + 306*x^7 + 188*x^8 - 180*x^9 - 40*x^10 + 2*x^11) / ((1 - x)*(1 + x + x^2)*(1 - 5*x^3 + 2*x^6)). - Colin Barker, Dec 03 2018

Example

Some solutions for n=4:
..2..3..0....0..3..2....3..2..3....2..3..0....3..0..2....3..2..0....2..1..2
..1..2..2....3..3..2....2..1..2....2..3..3....2..2..1....0..0..1....3..2..3
..2..3..3....2..2..1....3..2..0....1..2..2....3..3..2....2..3..0....0..2..3
..2..3..3....3..3..2....3..2..3....2..3..3....3..0..2....3..2..0....2..1..2
..1..2..2....0..3..2....2..1..2....2..0..3....2..2..1....0..0..0....3..2..3
..2..0..3....2..2..1....0..2..3....1..2..2....0..3..2....2..3..0....3..2..0

Crossrefs

Column 1 of A252278.

Sequence in context: A203888 A188447 A252278 * A080529 A261749 A058180

Adjacent sequences: A252268 A252269 A252270 * A252272 A252273 A252274

Keyword

nonn

Author

R. H. Hardin, Dec 16 2014

Status

approved