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A056267 Number of primitive (aperiodic) words of length n which contain exactly two different symbols. 3
0, 2, 6, 12, 30, 54, 126, 240, 504, 990, 2046, 4020, 8190, 16254, 32730, 65280, 131070, 261576, 524286, 1047540, 2097018, 4192254, 8388606, 16772880, 33554400, 67100670, 134217216, 268419060, 536870910, 1073708010, 2147483646 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

REFERENCES

M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia.

FORMULA

sum mu(d)*A000918(n/d) where d|n and n>0.

CROSSREFS

Cf. A000079, A000918, A027375.

Cf. A038199.

Sequence in context: A024701 A179674 A038199 * A133996 A080742 A005417

Adjacent sequences:  A056264 A056265 A056266 * A056268 A056269 A056270

KEYWORD

nonn

AUTHOR

Marks R. Nester (nesterm(AT)dpi.qld.gov.au)

EXTENSIONS

Corrected and extended by Franklin T. Adams-Watters and T. D. Noe (noe(AT)sspectra.com), Oct 25 2006

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Last modified February 15 15:20 EST 2012. Contains 205823 sequences.