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A056337 Number of primitive (aperiodic) reversible string structures with n beads using exactly three different colors. 1
0, 0, 1, 4, 15, 49, 160, 498, 1544, 4715, 14356, 43420, 131145, 394990, 1188564, 3572400, 10732065, 32224216, 96733636, 290317660, 871200664, 2614083394, 7843255300, 23531731530, 70599259170, 211805771345 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
A string and its reverse are considered to be equivalent. Permuting the colors will not change the 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]
LINKS
FORMULA
CROSSREFS
Column 3 of A276544.
Cf. A056319.
Sequence in context: A320460 A178704 A099167 * A053406 A225265 A143215
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified March 29 03:51 EDT 2024. Contains 371264 sequences. (Running on oeis4.)