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%I #19 Nov 07 2017 18:32:22
%S 1,2,1,3,2,2,1,4,3,2,2,3,3,2,2,5,2,4,2,3,1,2,2,4,5,3,2,3,4,2,1,6,2,4,
%T 2,5,3,4,3,4,3,2,3,3,4,2,2,5,4,5,2,3,4,4,2,4,2,4,4,3,5,2,3,7,3,2,2,6,
%U 2,2,2,4,3,4,5,3,2,3,2,5,5,6,3,3,4,2,4,4,4,5,3,3,1,2,4,6,3,5,4,5,4,4,3,4,2
%N Binary weight of sigma(n).
%C The sequence is considered in connection with A175522, A175524, A175526.
%C a(n)=1 if n is in A046528. - _Robert Israel_, Nov 07 2017
%H Antti Karttunen, <a href="/A175548/b175548.txt">Table of n, a(n) for n = 1..16384</a>
%H <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%H <a href="/index/Su#sums_of_divisors">Index entries for sequences related to sums of divisors</a>
%F a(n) = A000120(A000203(n)).
%e a(4) = 3 because the divisors of 4 add up to 7, a number which in binary is written as 3 ones.
%p seq(convert(convert(numtheory:-sigma(n),base,2),`+`),n=1..100); # _Robert Israel_, Nov 07 2017
%t Table[Plus@@IntegerDigits[DivisorSigma[1, n], 2], {n, 80}] (* _Alonso del Arte_, Dec 03 2010 *)
%o (PARI) a(n) = hammingweight(sigma(n)); \\ _Michel Marcus_, Feb 08 2016
%Y Cf. A000203, A000120, A046528, A175522, A175524, A175526.
%K nonn,base
%O 1,2
%A _Vladimir Shevelev_, Dec 03 2010
%E More terms from _Antti Karttunen_, Nov 07 2017
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