A002075 - OEIS

A002075

Number of equivalence classes with primitive period n of base 3 necklaces, where necklaces are equivalent under rotation and permutation of symbols.
(Formerly M1160 N0443)

1, 1, 2, 4, 8, 22, 52, 140, 366, 992, 2684, 7404, 20440, 56992, 159440, 448540, 1266080, 3587610, 10195276, 29057520, 83018728, 237737984, 682196948, 1961323740, 5648590728, 16294032160, 47071589778, 136171440600

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OFFSET

1,3

REFERENCES

N. J. Fine, Classes of periodic sequences, Illinois J. Math., 2 (1958), 285-302.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=1..28.

Index entries for sequences related to necklaces

FORMULA

Reference gives formula.

Sequence A002076 can be found as follows: Let F3(n) = this sequence, F3*(n) = function from A002076. Then F3*(n) = Sum_{ d divides n } F3(d).

CROSSREFS

Cf. A000013, A000048, A002076.

Sequence in context: A217975 A027385 A158324 * A337720 A293912 A122623

Adjacent sequences: A002072 A002073 A002074 * A002076 A002077 A002078

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane

EXTENSIONS

Better description and more terms from Mark Weston (mweston(AT)uvic.ca), Oct 07 2001

STATUS

approved