

A064287


Number of cyclotomic cosets C of 2 mod 2n+1 such that C is not equal to C, divided by 2.


5



0, 0, 1, 0, 0, 0, 1, 0, 0, 2, 1, 0, 0, 0, 3, 0, 2, 0, 1, 0, 0, 2, 1, 2, 2, 0, 1, 0, 0, 0, 5, 0, 0, 2, 1, 4, 2, 2, 1, 0, 0, 4, 1, 4, 4, 6, 1, 0, 0, 0, 1, 6, 0, 0, 1, 0, 2, 4, 3, 0, 2, 0, 9, 0, 0, 4, 3, 0, 0, 2, 1, 0, 4, 0, 5, 4, 6, 0, 1, 4, 0, 4, 1, 0, 0, 0, 3, 0, 0, 0, 1, 0, 2, 8, 1, 0, 6, 0, 1, 0, 2, 0, 3, 0, 0
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OFFSET

1,10


REFERENCES

F. J. MacWilliams and N. J. A. Sloane, The Theory of ErrorCorrecting Codes, Elsevier/North Holland, 1977, pp. 104105.


LINKS

Ray Chandler, Table of n, a(n) for n=1..10000


EXAMPLE

Mod 15 there are 4 cosets: {1, 2, 4, 8}, {3, 6, 12, 9}, {5, 10}, {7, 14, 13, 11}. Only the cosets {1, 2, 4, 8} and {7, 14, 13, 11} have the desired property, so a(7) = 2/2 = 1.


CROSSREFS

A006694(n) = A064286(n) + 2*a(n).
Sequence in context: A106278 A177517 A227819 * A196389 A128206 A103294
Adjacent sequences: A064284 A064285 A064286 * A064288 A064289 A064290


KEYWORD

nonn,nice,easy


AUTHOR

N. J. A. Sloane, Sep 25 2001


EXTENSIONS

Extended by Ray Chandler, Apr 25 2008


STATUS

approved



