OFFSET
1,2
COMMENTS
a(n)=1 if n is in A046528. - Robert Israel, Nov 07 2017
LINKS
EXAMPLE
a(4) = 3 because the divisors of 4 add up to 7, a number which in binary is written as 3 ones.
MAPLE
seq(convert(convert(numtheory:-sigma(n), base, 2), `+`), n=1..100); # Robert Israel, Nov 07 2017
MATHEMATICA
Table[Plus@@IntegerDigits[DivisorSigma[1, n], 2], {n, 80}] (* Alonso del Arte, Dec 03 2010 *)
PROG
(PARI) a(n) = hammingweight(sigma(n)); \\ Michel Marcus, Feb 08 2016
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Vladimir Shevelev, Dec 03 2010
EXTENSIONS
More terms from Antti Karttunen, Nov 07 2017
STATUS
approved