

A328657


Number of primitive (period n) nbead 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
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OFFSET

1,5


COMMENTS

Permuting the colors of the beads will not change the structure.


LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..200


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

Cf. A056362, A056514, A309784, A328038.
Sequence in context: A020181 A216134 A226908 * A335983 A113682 A291064
Adjacent sequences: A328654 A328655 A328656 * A328658 A328659 A328660


KEYWORD

nonn


AUTHOR

Andrew Howroyd, Oct 24 2019


STATUS

approved



