A056415 Number of step cyclic shifted sequences using exactly two different symbols.

0, 1, 2, 4, 4, 11, 8, 22, 20, 43, 28, 156, 72, 243, 366, 691, 520, 2635, 1608, 7384, 8866, 19399, 16768, 94482, 67560, 216273, 277532, 815556, 662368, 4500265, 2311468, 8466187, 13045106, 31593283, 40937604, 159772174, 103197488, 401913695

Offset: 1

Author

Marks R. Nester

Keywords

• nonn

Comments

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

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. A002729.

Formula

a(n) = A002729(n) - 2.

Extensions

Added more terms (from A002729), Joerg Arndt, Aug 27 2014