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A199944 Number of -n..n arrays x(0..2) of 3 elements with zeroth through 2nd differences all nonzero. 1
2, 36, 142, 376, 778, 1404, 2294, 3504, 5074, 7060, 9502, 12456, 15962, 20076, 24838, 30304, 36514, 43524, 51374, 60120, 69802, 80476, 92182, 104976, 118898, 134004, 150334, 167944, 186874, 207180, 228902, 252096, 276802, 303076, 330958, 360504 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A199943.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) -2*a(n-2) -2*a(n-3) +3*a(n-4) -a(n-5).

Conjectures from Colin Barker, May 17 2018: (Start)

G.f.: 2*x*(1 + 15*x + 19*x^2 + 13*x^3) / ((1 - x)^4*(1 + x)).

a(n) = 6*n - 10*n^2 + 8*n^3 for n even.

a(n) = -2 + 6*n - 10*n^2 + 8*n^3 for n odd.

(End)

EXAMPLE

Some solutions for n=6:

..5....2...-6...-6....1....5...-1....2....6....2...-3...-6...-4....1....5...-3

.-4....1...-3....3...-6....6...-2...-5...-2....4....3....2....1....4....3...-5

.-2...-1....6...-5....1....1....4....2....3....1...-5...-1...-5....6....6....3

CROSSREFS

Cf. A199943.

Sequence in context: A187509 A134785 A143745 * A227927 A007757 A141217

Adjacent sequences:  A199941 A199942 A199943 * A199945 A199946 A199947

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 12 2011

STATUS

approved

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Last modified July 22 05:47 EDT 2019. Contains 325213 sequences. (Running on oeis4.)