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A276300 Number of 3 X n 0..2 arrays with no element equal to any value at offset (-2,-1) (-1,1) or (0,-1) and new values introduced in order 0..2. 1
5, 11, 45, 173, 693, 2765, 11061, 44237, 176949, 707789, 2831157, 11324621, 45298485, 181193933, 724775733, 2899102925, 11596411701, 46385646797, 185542587189, 742170348749, 2968681394997, 11874725579981, 47498902319925 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) + a(n-2) - 4*a(n-3) for n>4.
Conjectures from Colin Barker, Feb 05 2019: (Start)
G.f.: x*(5 - 9*x - 4*x^2 + 2*x^3) / ((1 - x)*(1 + x)*(1 - 4*x)).
a(n) = (8 + 27*4^n) / 40 for n>1 and even.
a(n) = (72 + 27*4^n) / 40 for n>1 and odd.
(End)
EXAMPLE
Some solutions for n=4:
..0..1..2..1. .0..1..0..1. .0..1..0..1. .0..1..0..2. .0..1..2..1
..0..1..2..0. .0..2..0..1. .2..1..2..1. .0..2..1..2. .0..1..2..0
..2..1..2..0. .0..2..0..2. .2..1..0..2. .1..2..0..2. .0..1..2..1
CROSSREFS
Row 3 of A276299.
Sequence in context: A262020 A222368 A333114 * A222476 A097056 A092358
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 28 2016
STATUS
approved

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Last modified April 22 17:45 EDT 2024. Contains 371906 sequences. (Running on oeis4.)