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A199531 Number of -n..n arrays x(0..3) of 4 elements with zero sum and no two consecutive zero elements. 1
12, 72, 212, 464, 860, 1432, 2212, 3232, 4524, 6120, 8052, 10352, 13052, 16184, 19780, 23872, 28492, 33672, 39444, 45840, 52892, 60632, 69092, 78304, 88300, 99112, 110772, 123312, 136764, 151160, 166532, 182912, 200332, 218824, 238420, 259152 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A199530.

LINKS

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

FORMULA

Empirical: a(n) = (16/3)*n^3 + 8*n^2 - (4/3)*n.

Conjectures from Colin Barker, May 15 2018: (Start)

G.f.: 4*x*(3 + 6*x - x^2) / (1 - x)^4.

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>4.

(End)

EXAMPLE

Some solutions for n=5:

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

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

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

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

CROSSREFS

Cf. A199530.

Sequence in context: A101523 A143698 A304164 * A188660 A047928 A300847

Adjacent sequences:  A199528 A199529 A199530 * A199532 A199533 A199534

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 07 2011

STATUS

approved

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Last modified October 15 09:22 EDT 2019. Contains 328026 sequences. (Running on oeis4.)