A288621 Number of step shifted (decimated) sequence structures of length n using an infinite alphabet.

1, 2, 4, 11, 18, 117, 162, 1205, 3621, 29271, 68086, 1069614, 2305158, 31825670, 172974370, 1311400891, 5179123522, 113680235941, 324041807958, 6466011855715, 39572612670818, 450671611457619, 2006909406239780, 55745145216877102, 231929517217884081

Offset: 1

Author

Andrew Howroyd, Jun 11 2017

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

Row sums of A288620.

Cf. A056391, A056371, A288628.

Programs

PARI

\\ see A056391 for Polya enumeration functions
a(n) = NonequivalentStructs(StepShiftPerms(n), n); \\ Andrew Howroyd, Oct 14 2017