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%I A066519 #6 Jun 24 2014 01:08:18
%S A066519 1,1,3,3,6,2,4,7,2,6,7,3,1,4,3,8,7,2,1,3,5,10,2,1,3,3,2,1,5,1,1,1,4,4,
%T A066519 2,2,2,9,2,6,9,1,1,4,4,1,3,6,1,3,22,1,9,1,1,2,2,4,7,3,5,4,1,2,20,1,2,
%U A066519 6,1,4,4,9,5,1,4,5,2,7,8,2,2,9,2,2,1,5,3,1,4,1,12,16,13,5,1,9,2,1,3,3
%N A066519 Gaps between successive numbers with an anti-divisor class sum of zero.
%C A066519 See A066272 for definition of anti-divisor.
%H A066519 Jon Perry, <a href="http://www.users.globalnet.co.uk/~perry/maths/antidivisorother2.htm">Class sums</a>
%e A066519 f(1)=f(2)=f(3)=0, f(4)=1, f(5)=-1, f(6)=0, so the first 3 gaps are 1, 1, 3.
%t A066519 a[ n_ ] := Sum[ Which[ Mod[ n, d ]==(d-1)/2, -1, Mod[ n, d ]==(d+1)/2, 1, True, 0 ], {d, 2, n-1} ]; z=Select[ Range[ 1, 500 ], a[ # ]==0& ]; Drop[ z, 1 ]-Drop[ z, -1 ]
%Y A066519 Cf. A066518.
%K A066519 nonn
%O A066519 1,3
%A A066519 _Jon Perry_, Jan 06 2002
%E A066519 Edited by _Dean Hickerson_, Jan 17 2002

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