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A056305
Number of primitive (period n) n-bead necklace structures using exactly four different colored beads.
3
0, 0, 0, 1, 2, 13, 50, 220, 866, 3435, 13250, 51061, 194810, 742601, 2823764, 10738660, 40843370, 155493872, 592614050, 2261622287, 8643289484, 33080907357, 126797503250, 486710920300, 1870851589552
OFFSET
1,5
COMMENTS
Turning over the necklace is not allowed. Colors may be permuted without changing the necklace structure.
REFERENCES
M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]
FORMULA
Sum mu(d)*A056297(n/d) where d|n. Alternatively, A056300(n)-A002075(n)..
CROSSREFS
Column 4 of A107424.
Cf. A056289.
Sequence in context: A072416 A319759 A254784 * A056297 A241892 A037383
KEYWORD
nonn
STATUS
approved