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%I A286530 #11 May 21 2017 14:32:38
%S A286530 1,1,0,-1,0,0,1,2,3,0,0,0,2,2,-2,-1,0,2,2,-2,-1,0,1,-2,3,4,-2,-2,0,-4,
%T A286530 2,-2,-2,0,0,-3,2,4,-2,2,0,-2,4,0,-2,2,1,-6,3,2,0,-2,2,-4,-2,-1,-2,0,
%U A286530 0,0,4,4,-2,-5,0,-4,2,-2,-2,0,0,0,4,4,-1,-2,1,-4,3,2,-1,0,2,0,-2,8,0,4,2,-4,0,0,-2,2,2,0,4,2,2,-7,0,0,6,2,-6,4,0,4,2
%N A286530 a(n) = d(n+d(n)) - d(n), where d(n) is the number of divisors of n (A000005).
%H A286530 Antti Karttunen, <a href="/A286530/b286530.txt">Table of n, a(n) for n = 1..10000</a>
%F A286530 a(n) = A286529(n) - A000005(n) = A000005(n+A000005(n)) - A000005(n).
%t A286530 Table[DivisorSigma[0, n + DivisorSigma[0, n]] - DivisorSigma[0, n], {n, 109}] (* _Michael De Vlieger_, May 21 2017 *)
%o A286530 (PARI) A286530(n) = (numdiv(n+numdiv(n)) - numdiv(n));
%o A286530 (Scheme) (define (A286530 n) (- (A286529 n) (A000005 n)))
%o A286530 (Python)
%o A286530 from sympy import divisor_count as d
%o A286530 def a(n): return d(n + d(n)) - d(n) # _Indranil Ghosh_, May 21 2017
%Y A286530 Cf. A000005, A286529, A286480.
%Y A286530 Cf. A175304 (the positions of zeros).
%K A286530 sign
%O A286530 1,8
%A A286530 _Antti Karttunen_, May 21 2017

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