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A221462 Number of 0..7 arrays of length n with each element unequal to at least one neighbor, starting with 0 1
0, 7, 49, 392, 3087, 24353, 192080, 1515031, 11949777, 94253656, 743424031, 5863743809, 46250174880, 364797430823, 2877333239921, 22694914695208, 179005735545903, 1411904551687777, 11136372010635760, 87837935936264759 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 7 of A221463

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..134

FORMULA

Empirical: a(n) = 7*a(n-1) +7*a(n-2)

EXAMPLE

Some solutions for n=6

..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

..6....5....5....7....7....1....7....4....1....3....1....4....2....5....6....1

..1....4....5....3....2....2....4....7....1....5....2....3....5....2....7....2

..1....1....0....4....0....3....6....5....2....1....4....3....1....7....3....5

..4....6....4....4....3....7....1....2....1....1....2....0....0....4....5....1

..2....2....6....7....0....1....2....0....5....2....1....4....6....0....0....0

CROSSREFS

Sequence in context: A144820 A324353 A199554 * A090016 A005924 A145358

Adjacent sequences:  A221459 A221460 A221461 * A221463 A221464 A221465

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 17 2013

STATUS

approved

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Last modified December 5 17:42 EST 2019. Contains 329768 sequences. (Running on oeis4.)