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A199833
Number of -n..n arrays of 4 elements with zero sum and no two neighbors summing to zero.
1
4, 40, 140, 336, 660, 1144, 1820, 2720, 3876, 5320, 7084, 9200, 11700, 14616, 17980, 21824, 26180, 31080, 36556, 42640, 49364, 56760, 64860, 73696, 83300, 93704, 104940, 117040, 130036, 143960, 158844, 174720, 191620, 209576, 228620, 248784
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = (16/3)*n^3 - (4/3)*n = 4*A000447(n).
Empirical: G.f.: 4*x*(1+6*x+x^2) / (x-1)^4 . - R. J. Mathar, Aug 01 2014
Empirical: partial sums of A016826. - Sean A. Irvine, Jul 13 2022
EXAMPLE
Some solutions for n=3:
0 -3 -3 0 0 0 -1 1 1 -1 0 0 -3 -2 -1 -2
-2 2 -1 3 1 1 0 1 -2 2 -2 1 2 1 -3 0
3 3 2 0 2 1 -1 -3 1 0 0 0 -1 -2 1 1
-1 -2 2 -3 -3 -2 2 1 0 -1 2 -1 2 3 3 1
CROSSREFS
Row 2 of A199832.
Sequence in context: A063997 A355841 A187378 * A248964 A224086 A271013
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 11 2011
STATUS
approved