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A202963 Number of arrays of 3 integers in -n..n with sum zero and adjacent elements differing in absolute value 1
2, 6, 20, 36, 62, 90, 128, 168, 218, 270, 332, 396, 470, 546, 632, 720, 818, 918, 1028, 1140, 1262, 1386, 1520, 1656, 1802, 1950, 2108, 2268, 2438, 2610, 2792, 2976, 3170, 3366, 3572, 3780, 3998, 4218, 4448, 4680, 4922, 5166, 5420, 5676, 5942, 6210, 6488 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 1 of A202962

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

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

Empirical: G.f. x*(2+2*x+8*x^2)/(1-2*x+2*x^3-x^4). [Colin Barker, Jan 04 2012]

EXAMPLE

Some solutions for n=5

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

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

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

CROSSREFS

Sequence in context: A181558 A218883 A353699 * A130315 A087150 A323724

Adjacent sequences:  A202960 A202961 A202962 * A202964 A202965 A202966

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 26 2011

STATUS

approved

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Last modified October 6 12:35 EDT 2022. Contains 357264 sequences. (Running on oeis4.)