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A328657
Number of primitive (period n) n-bead bracelet structures which are not periodic palindromes using a maximum of three different colored beads.
2
0, 0, 1, 1, 4, 9, 26, 66, 183, 488, 1342, 3690, 10220, 28470, 79720, 224230, 633040, 1793727, 5097638, 14528640, 41509364, 118868750, 341098474, 980661510, 2824295364, 8147015352, 23535794889, 68085719208, 197213728060, 571919889400, 1660412355602, 4825573629390
OFFSET
1,5
COMMENTS
Permuting the colors of the beads will not change the structure.
LINKS
FORMULA
a(n) = Sum_{k=1..3} A309784(n, k).
a(n) = A056362(n) - A056514(n).
EXAMPLE
For n <= 5, the structures are the same as in A328038.
For n = 6, the 9 bracelet structures have the patterns: AABABB, ABCCCC, ABBCCC, ABBBCB, ABBCBC, ABBCCB, ABCBBC, AABBCC, AABCBC.
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Oct 24 2019
STATUS
approved