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 A290090 a(n) is the number of proper divisors of n that are odious (A000069). 4
 0, 1, 1, 2, 1, 2, 1, 3, 1, 2, 1, 3, 1, 3, 1, 4, 1, 2, 1, 3, 2, 3, 1, 4, 1, 3, 1, 5, 1, 2, 1, 5, 2, 2, 2, 3, 1, 3, 2, 4, 1, 5, 1, 5, 1, 2, 1, 5, 2, 3, 1, 5, 1, 2, 2, 7, 2, 2, 1, 3, 1, 3, 3, 6, 2, 4, 1, 3, 1, 5, 1, 4, 1, 3, 2, 5, 3, 4, 1, 5, 1, 3, 1, 8, 1, 2, 1, 7, 1, 2, 3, 3, 2, 3, 2, 6, 1, 5, 2, 5, 1, 2, 1, 7, 4, 2, 1, 3, 1, 5, 2, 9, 1, 4, 1, 3, 2, 3, 2, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS If n is odd and k >= 1, then a(2^k*n) = (k+1)*n+k if n is in A000069 and (k+1)*n if n is not in A000069. - Robert Israel, Oct 03 2017 LINKS Antti Karttunen, Table of n, a(n) for n = 1..16385 FORMULA a(n) = Sum_{d|n, d convert(convert(t, base, 2), `+`)::odd, numtheory:-divisors(n) minus {n})) end proc: map(f, [\$1..200]); # Robert Israel, Oct 03 2017 MATHEMATICA Table[DivisorSum[n, 1 &, And[OddQ@ DigitCount[#, 2, 1], # < n] &], {n, 120}] (* Michael De Vlieger, Oct 03 2017 *) PROG (PARI) A290090(n) = sumdiv(n, d, (d

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Last modified January 22 23:00 EST 2019. Contains 319365 sequences. (Running on oeis4.)