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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

%I

%S 2,6,20,36,62,90,128,168,218,270,332,396,470,546,632,720,818,918,1028,

%T 1140,1262,1386,1520,1656,1802,1950,2108,2268,2438,2610,2792,2976,

%U 3170,3366,3572,3780,3998,4218,4448,4680,4922,5166,5420,5676,5942,6210,6488

%N Number of arrays of 3 integers in -n..n with sum zero and adjacent elements differing in absolute value

%C Row 1 of A202962

%H R. H. Hardin, <a href="/A202963/b202963.txt">Table of n, a(n) for n = 1..210</a>

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

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

%e Some solutions for n=5

%e .-2....1....3...-4...-2...-4....5...-1...-1....2....2....2...-2....2....1....4

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

%e ..5...-1...-4....3....3....1...-4...-4...-1....2...-2...-3...-1...-5....1...-3

%K nonn

%O 1,1

%A _R. H. Hardin_ Dec 26 2011

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Last modified December 2 07:06 EST 2022. Contains 358493 sequences. (Running on oeis4.)