%I A064287
%S A064287 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,
%T A064287 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,
%U A064287 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
%N A064287 Number of cyclotomic cosets C of 2 mod 2n+1 such that -C is not equal 
               to C, divided by 2.
%D A064287 F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting 
               Codes, Elsevier/North Holland, 1977, pp. 104-105.
%H A064287 Ray Chandler, <a href="b064287.txt">Table of n, a(n) for n=1..10000</
               a>
%e A064287 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.
%Y A064287 A006694(n) = A064286(n) + 2*a(n).
%Y A064287 Sequence in context: A116402 A093323 A106278 this_sequence A128206 A103294 
               A079680
%Y A064287 Adjacent sequences: A064284 A064285 A064286 this_sequence A064288 A064289 
               A064290
%K A064287 nonn,nice,easy
%O A064287 1,10
%A A064287 N. J. A. Sloane (njas(AT)research.att.com), Sep 25 2001
%E A064287 Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Apr 25 2008