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A056393
Number of step shifted (decimated) sequence structures using a maximum of four different symbols.
4
1, 2, 4, 11, 17, 107, 131, 811, 1893, 11107, 17599, 179371, 233449, 1866057, 5603787, 22469291, 44744047, 477262537, 636308685, 5732457131, 15272176697, 73301054891, 133274359129, 1466413263531
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..4} A288620(n, k). - Andrew Howroyd, Jun 13 2017
CROSSREFS
Sequence in context: A283357 A182642 A218911 * A319417 A056394 A056395
KEYWORD
nonn
STATUS
approved