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A208799
Number of n-bead necklaces labeled with numbers -2..2 allowing reversal, with sum zero and three times sum of squares <= n*(2)*(2+1).
1
1, 2, 4, 11, 33, 105, 395, 1612, 6323, 27727, 115117, 506417, 2240045, 9863620, 44646673, 200485659, 912889175, 4178508224, 19142413757, 88521250696, 409486689399, 1904094176208, 8884513374761, 41533090926064, 194937511464985
OFFSET
1,2
LINKS
EXAMPLE
Some solutions for n=6:
.-2...-1...-2...-1...-2...-2...-2...-2...-1...-2...-2...-1...-1...-1...-2...-1
..0....1....1....0....1....0...-1....1....0....0....0...-1....0....0...-1...-1
..1...-1....0...-1...-1....0....1...-1...-1....0....1....0....0...-1....0....0
..0....1....0....0....0....1....2...-1....0....1...-1....1....1....1....2...-1
..1...-1...-1....0....1....1....0....1....2....0....0....0...-1...-1....0....2
..0....1....2....2....1....0....0....2....0....1....2....1....1....2....1....1
CROSSREFS
Column 2 of A208805.
Sequence in context: A035354 A220902 A249945 * A340329 A268323 A268324
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 01 2012
EXTENSIONS
a(20)-a(25) from Andrew Howroyd, Mar 02 2017
STATUS
approved