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A266008 Number of n X 4 integer arrays with each element equal to the number of horizontal and antidiagonal neighbors equal to itself. 1
1, 4, 4, 9, 14, 21, 44, 52, 129, 138, 361, 388, 980, 1129, 2614, 3325, 6924, 9764, 18369, 28370, 49105, 81348, 132708, 230281, 362782, 644837, 1001644, 1790932, 2785729, 4947162, 7781177, 13626564, 21772724, 37503337, 60913350, 103288269, 170189068 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = -a(n-1) + 3*a(n-2) + 3*a(n-3) - a(n-4).
Empirical g.f.: x*(1 + 2*x)*(1 + 3*x - x^2) / (1 + x - 3*x^2 - 3*x^3 + x^4). - Colin Barker, Jan 09 2019
EXAMPLE
Some solutions for n=4:
..0..2..2..0....0..2..2..0....1..1..2..2....0..2..2..1....1..1..2..2
..2..2..1..1....2..2..1..1....0..2..2..0....2..2..1..0....0..2..2..0
..0..2..2..0....0..2..2..1....1..1..2..2....0..2..2..1....0..1..2..2
..2..2..1..1....2..2..1..0....0..2..2..0....2..2..1..0....1..2..2..0
CROSSREFS
Column 4 of A266012.
Sequence in context: A341678 A050218 A165996 * A284628 A262811 A294749
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 20 2015
STATUS
approved

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Last modified June 13 03:35 EDT 2024. Contains 373366 sequences. (Running on oeis4.)