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A221593
Number of 0..5 arrays of length n with each element differing from at least one neighbor by 1 or less.
1
0, 16, 44, 256, 1068, 5082, 22912, 105586, 482204, 2210256, 10115926, 46327024, 212107056, 971225210, 4446995942, 20362020404, 93233503292, 426898240022, 1954682503544, 8950108307086, 40980784959354, 187642965834692
OFFSET
1,2
COMMENTS
Column 5 of A221596.
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) +3*a(n-2) -6*a(n-3) +19*a(n-4) +5*a(n-5) +a(n-6).
Empirical g.f.: 2*x^2*(8 - 10*x + 16*x^2 + 4*x^3 + x^4) / (1 - 4*x - 3*x^2 + 6*x^3 - 19*x^4 - 5*x^5 - x^6). - Colin Barker, Oct 19 2017
EXAMPLE
Some solutions for n=6
..2....4....0....0....3....5....2....1....2....4....5....4....2....2....1....3
..2....3....1....0....3....4....1....0....3....3....5....3....2....1....1....4
..4....0....5....3....1....2....2....0....2....5....1....2....3....4....2....5
..4....0....5....4....2....2....2....2....4....4....1....5....1....4....3....5
..1....4....3....4....3....0....1....3....5....1....1....5....1....4....2....1
..2....5....2....5....3....1....1....3....4....0....2....5....0....4....3....0
CROSSREFS
Sequence in context: A211582 A204032 A192143 * A300962 A359704 A051868
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 20 2013
STATUS
approved