

A326660


Number of nbead asymmetric bracelets with exactly 3 different colored beads.


3



0, 0, 1, 3, 12, 34, 111, 315, 933, 2622, 7503, 21033, 59472, 167118, 472120, 1332945, 3777600, 10720869, 30516447, 87032994, 248820704, 712743768, 2045784183, 5882367570, 16942974048, 48876558318, 141204944529, 408494941773, 1183247473872, 3431450670601
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OFFSET

1,4


COMMENTS

Asymmetric bracelets are those primitive (period n) bracelets that when turned over are different from themselves.


LINKS

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


FORMULA

a(n) = A032240(n)  3*A032239(n) for n >= 3.
Moebius transform of A305542.


EXAMPLE

Case n = 4: There are 3 distinct asymmetric bracelets with exactly 3 colors which are aabc, abbc, abcc.


CROSSREFS

Column k=3 of A309651.
Cf. A032239, A032240, A056343, A056349, A305542, A326789.
Sequence in context: A073372 A305023 A026573 * A225075 A293267 A295363
Adjacent sequences: A326657 A326658 A326659 * A326661 A326662 A326663


KEYWORD

nonn


AUTHOR

Andrew Howroyd, Sep 12 2019


STATUS

approved



