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A056392
Number of step shifted (decimated) sequence structures using a maximum of three different symbols.
4
1, 2, 4, 10, 14, 70, 68, 332, 577, 2510, 2980, 23372, 22218, 133150, 300964, 909382, 1345634, 10767202, 10762820, 72957100, 145362932, 523029526, 713213956, 5893709440, 7060765733, 35303782550
OFFSET
1,2
COMMENTS
See A056371 for an explanation of step shifts. 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]
FORMULA
Use de Bruijn's generalization of Polya's enumeration theorem as discussed in reference.
a(n) = Sum_{k=1..3} A288620(n, k). - Andrew Howroyd, Jun 13 2017
CROSSREFS
Sequence in context: A236547 A078775 A351160 * A080149 A217134 A351927
KEYWORD
nonn
STATUS
approved