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A252713
Number of (n+2) X (2+2) 0..3 arrays with every consecutive three elements in every row and diagonal having exactly two distinct values, and in every column and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order.
1
52, 46, 56, 76, 102, 154, 220, 306, 478, 700, 990, 1570, 2332, 3330, 5326, 7996, 11502, 18514, 28060, 40626, 65758, 100540, 146430, 238210, 367132, 537570, 878446, 1363516, 2005902, 3290674, 5139100, 7590546, 12493438, 19611580, 29063070
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = a(n-1) + 7*a(n-3) - 7*a(n-4) - 12*a(n-6) + 12*a(n-7) for n>9.
Empirical g.f.: 2*x*(26 - 3*x + 5*x^2 - 172*x^3 + 34*x^4 - 9*x^5 + 275*x^6 - 84*x^7 - 36*x^8) / ((1 - x)*(1 - 3*x^3)*(1 - 4*x^3)). - Colin Barker, Dec 05 2018
EXAMPLE
Some solutions for n=4:
..0..1..0..0....0..0..1..1....0..0..1..0....0..0..1..0....0..1..0..0
..2..2..0..2....2..2..0..0....0..2..2..0....0..2..2..0....1..1..2..1
..1..0..0..1....3..3..2..2....0..1..0..0....0..3..0..0....2..1..1..2
..0..1..0..0....1..1..3..3....0..0..1..0....0..0..3..0....0..1..0..0
..2..2..0..2....0..0..1..1....0..2..2..0....0..1..1..0....1..1..2..1
..3..0..0..1....2..2..0..2....0..1..0..0....0..2..0..0....2..1..1..2
CROSSREFS
Column 2 of A252719.
Sequence in context: A033372 A126767 A143723 * A249404 A327374 A327109
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 20 2014
STATUS
approved