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A199705 Number of -n..n arrays x(0..2) of 3 elements with zero sum and no two neighbors equal. 1
6, 14, 32, 52, 82, 114, 156, 200, 254, 310, 376, 444, 522, 602, 692, 784, 886, 990, 1104, 1220, 1346, 1474, 1612, 1752, 1902, 2054, 2216, 2380, 2554, 2730, 2916, 3104, 3302, 3502, 3712, 3924, 4146, 4370, 4604, 4840, 5086, 5334, 5592, 5852, 6122, 6394, 6676 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A199704.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4).

Conjectures from Colin Barker, May 16 2018: (Start)

G.f.: 2*x*(3 + x + 2*x^2) / ((1 - x)^3*(1 + x)).

a(n) = n + 3*n^2 for n even.

a(n) = 2 + n + 3*n^2 for n odd.

(End)

EXAMPLE

Some solutions for n=5:

..1...-5....1....1....3...-1...-2....3....1....2....2...-5....3...-3...-3....4

..3....3...-5....4....0...-4....3...-3...-1...-5....0....5...-2....4....0....1

.-4....2....4...-5...-3....5...-1....0....0....3...-2....0...-1...-1....3...-5

CROSSREFS

Cf. A199704.

Sequence in context: A024932 A273365 A271996 * A225972 A078836 A142875

Adjacent sequences:  A199702 A199703 A199704 * A199706 A199707 A199708

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 09 2011

STATUS

approved

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Last modified August 25 21:00 EDT 2019. Contains 326324 sequences. (Running on oeis4.)