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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,10

REFERENCES

F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier/North Holland, 1977, pp. 104-105.

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

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Last modified November 13 11:24 EST 2018. Contains 317133 sequences. (Running on oeis4.)