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A328038 Number of primitive (period n) n-bead bracelet structures which are not periodic palindromes using exactly three different colored beads. 4
0, 0, 1, 1, 4, 8, 25, 62, 176, 470, 1311, 3620, 10094, 28209, 79236, 223270, 631240, 1790213, 5090995, 14515788, 41484907, 118821599, 341008317, 980487770, 2823961866, 8146372122, 23534556225, 68083326558, 197209108054, 571910949743, 1660395053569, 4825540091342 (list; graph; refs; listen; history; text; internal format)
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) = A056367(n) - A056519(n).

EXAMPLE

For n = 3, the 1 bracelet structure has the pattern: ABC.

For n = 4, the 1 bracelet structure has the pattern: AABC.

For n = 5, the 4 bracelet structures have the patterns: AAABC, AABAC, AABBC, ABABC. The pattern ABBAC is excluded because it is a periodic palindrome.

For n = 6, the 8 bracelet structures have the patterns: ABCCCC, ABBCCC, ABBBCB, ABBCBC, ABBCCB, ABCBBC, AABBCC, AABCBC.

CROSSREFS

Column 3 of A309784.

Cf. A056367, A056519, A328035, A328039, A328657.

Sequence in context: A292548 A000964 A297458 * A107840 A046736 A174171

Adjacent sequences:  A328035 A328036 A328037 * A328039 A328040 A328041

KEYWORD

nonn

AUTHOR

Andrew Howroyd, Oct 02 2019

STATUS

approved

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Last modified August 4 20:00 EDT 2020. Contains 336202 sequences. (Running on oeis4.)