A288628 Number of step cyclic shifted sequence structures of length n using an infinite alphabet.

1, 2, 3, 7, 8, 37, 37, 223, 468, 3203, 6398, 93103, 178663, 2282131, 11561896, 82120878, 304719416, 6316222138, 17055376113, 323332552319, 1884432112761, 20485110860448, 87256977757852, 2322728266726152, 9277181270824996, 159074512149044084, 1122874592283076868

Offset: 1

Author

Andrew Howroyd, Jun 11 2017

Keywords

• nonn

Comments

See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. 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 A288627.

Cf. A056391, A056371, A288621.

Programs

PARI

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