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A200155 revision #7

A200155
Number of 0..n arrays x(0..3) of 4 elements with zero 3rd difference.
2
4, 9, 22, 41, 66, 107, 158, 219, 304, 403, 516, 661, 824, 1005, 1226, 1469, 1734, 2047, 2386, 2751, 3172, 3623, 4104, 4649, 5228, 5841, 6526, 7249, 8010, 8851, 9734, 10659, 11672, 12731, 13836, 15037, 16288, 17589, 18994, 20453, 21966, 23591, 25274, 27015
OFFSET
1,1
COMMENTS
Row 4 of A200154.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) -a(n-2) +2*a(n-3) -4*a(n-4) +2*a(n-5) -a(n-6) +2*a(n-7) -a(n-8).
EXAMPLE
Some solutions for n=6
..3....4....2....0....0....4....4....3....3....3....2....2....6....3....5....3
..3....4....6....4....1....1....5....1....0....0....2....2....1....4....1....4
..4....3....6....6....3....0....4....1....0....1....3....2....1....4....0....3
..6....1....2....6....6....1....1....3....3....6....5....2....6....3....2....0
CROSSREFS
Sequence in context: A158140 A290647 A105314 * A002835 A253289 A032288
KEYWORD
nonn
AUTHOR
R. H. Hardin Nov 13 2011
STATUS
proposed