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A253018
Number of (n+2) X (1+2) 0..3 arrays with every consecutive three elements in every row and column not having exactly two distinct values, and in every diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.
1
25, 37, 51, 63, 105, 153, 189, 315, 459, 567, 945, 1377, 1701, 2835, 4131, 5103, 8505, 12393, 15309, 25515, 37179, 45927, 76545, 111537, 137781, 229635, 334611, 413343, 688905, 1003833, 1240029, 2066715, 3011499, 3720087, 6200145, 9034497, 11160261
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-3) for n>5.
Empirical g.f.: x*(25 + 37*x + 51*x^2 - 12*x^3 - 6*x^4) / (1 - 3*x^3). - Colin Barker, Dec 08 2018
EXAMPLE
Some solutions for n=4:
..0..1..2....0..0..0....0..1..2....0..1..2....0..0..0....0..1..2....0..1..2
..2..1..0....1..0..2....0..0..0....3..1..0....1..2..0....2..2..2....3..0..2
..1..1..1....2..0..3....0..2..1....1..1..1....2..1..0....1..3..2....2..2..2
..0..1..2....0..0..0....0..1..2....0..1..3....0..0..0....3..1..2....1..3..2
..2..1..0....3..0..2....0..0..0....2..1..0....1..2..0....2..2..2....3..1..2
..1..1..1....2..0..3....0..2..1....1..1..1....2..3..0....1..0..2....2..2..2
CROSSREFS
Column 1 of A253025.
Sequence in context: A079270 A253025 A127022 * A120148 A038516 A080386
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 26 2014
STATUS
approved