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A252855
Number of (n+2) X (2+2) 0..2 arrays with every consecutive three elements in every row, column, diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.
1
279, 432, 738, 1296, 2502, 4986, 9936, 20052, 40770, 82872, 168516, 343062, 698688, 1422756, 2897190, 5900472, 12017268, 24474006, 49843512, 101512980, 206743590, 421055928, 857529828, 1746463734, 3556879416, 7244001396, 14753268774
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = a(n-1) + a(n-2) + 3*a(n-3) + a(n-4) - 3*a(n-5) - 4*a(n-6) - 2*a(n-7) + 2*a(n-8) + 2*a(n-9).
Empirical g.f.: 9*x*(31 + 17*x + 3*x^2 - 79*x^3 - 123*x^4 - 69*x^5 + 26*x^6 + 92*x^7 + 52*x^8) / ((1 - x)*(1 + x + x^2)*(1 - x - x^2 - 2*x^3 - 2*x^4 + 2*x^5 + 2*x^6)). - Colin Barker, Dec 07 2018
EXAMPLE
Some solutions for n=4:
..0..1..0..0....0..1..0..1....0..1..0..0....0..1..1..2....0..1..0..1
..2..0..0..1....1..1..0..0....2..2..0..0....2..2..1..1....0..1..1..2
..2..1..1..0....0..0..1..0....2..1..2..1....2..2..0..2....1..2..1..2
..0..0..1..1....1..0..0..2....1..2..2..1....1..0..0..2....1..1..0..0
..0..0..2..0....0..1..1..2....1..2..1..2....1..2..2..0....2..2..0..0
..1..2..2..0....1..1..0..0....0..0..2..2....2..0..2..2....2..2..1..1
CROSSREFS
Column 2 of A252861.
Sequence in context: A062384 A053345 A032505 * A331265 A038656 A160116
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 23 2014
STATUS
approved