A064287 - OEIS

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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.

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: A339829 A177517 A227819 * A196389 A128206 A371417

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