A056393 Number of step shifted (decimated) sequence structures using a maximum of four different symbols.

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

Author

Marks R. Nester

Keywords

• nonn

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]

Crossrefs

Cf. A056373, A288620.

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