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

1,2

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]

Links

Table of n, a(n) for n=1..25.

Prog

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

Crossrefs

Row sums of A288620.

Cf. A056391, A056371, A288628.

Sequence in context: A319417 A056394 A056395 * A053031 A018674 A076518

Adjacent sequences: A288618 A288619 A288620 * A288622 A288623 A288624

Keyword

nonn

Author

Andrew Howroyd, Jun 11 2017

Status

approved