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A056444
Number of primitive (period n) step cyclic shifted sequence structures using exactly two different symbols.
0
0, 1, 1, 2, 2, 5, 4, 10, 9, 22, 14, 78, 36, 124, 180, 343, 260, 1329, 804, 3732, 4428, 9742, 8384, 47364, 33778, 108292, 138756, 408244, 331184, 2251604, 1155734
OFFSET
1,4
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. Identical to A056439 for n>1.
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]
FORMULA
a(n) = A056439(n) - A000007(n-1).
CROSSREFS
Cf. A056424.
Sequence in context: A332895 A095057 A056439 * A319925 A112472 A240412
KEYWORD
nonn
STATUS
approved