A208799 - OEIS

%I #13 Mar 12 2017 22:44:16

%S 1,2,4,11,33,105,395,1612,6323,27727,115117,506417,2240045,9863620,

%T 44646673,200485659,912889175,4178508224,19142413757,88521250696,

%U 409486689399,1904094176208,8884513374761,41533090926064,194937511464985

%N 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).

%H Andrew Howroyd, <a href="/A208799/b208799.txt">Table of n, a(n) for n = 1..100</a>

%e Some solutions for n=6:

%e .-2...-1...-2...-1...-2...-2...-2...-2...-1...-2...-2...-1...-1...-1...-2...-1

%e ..0....1....1....0....1....0...-1....1....0....0....0...-1....0....0...-1...-1

%e ..1...-1....0...-1...-1....0....1...-1...-1....0....1....0....0...-1....0....0

%e ..0....1....0....0....0....1....2...-1....0....1...-1....1....1....1....2...-1

%e ..1...-1...-1....0....1....1....0....1....2....0....0....0...-1...-1....0....2

%e ..0....1....2....2....1....0....0....2....0....1....2....1....1....2....1....1

%Y Column 2 of A208805.

%K nonn

%O 1,2

%A _R. H. Hardin_, Mar 01 2012

%E a(20)-a(25) from _Andrew Howroyd_, Mar 02 2017