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A056429 Number of step cyclic shifted sequence structures using a maximum of two different symbols. 4
1, 2, 2, 4, 3, 8, 5, 14, 11, 26, 15, 88, 37, 130, 184, 357, 261, 1346, 805, 3760, 4434, 9758, 8385, 47462, 33781, 108330, 138767, 408376, 331185, 2251816, 1155735 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. Permuting the symbols 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

Table of n, a(n) for n=1..31.

FORMULA

Use de Bruijn's generalization of Polya's enumeration theorem as discussed in reference.

a(n) = A288627(n, 2) + 1. - Andrew Howroyd, Jun 13 2017

CROSSREFS

Cf. A002729, A288627.

Sequence in context: A285620 A185959 A006799 * A133806 A283717 A185333

Adjacent sequences:  A056426 A056427 A056428 * A056430 A056431 A056432

KEYWORD

nonn

AUTHOR

Marks R. Nester

STATUS

approved

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Last modified March 8 20:14 EST 2021. Contains 341953 sequences. (Running on oeis4.)