A227873 Sum of odious divisors of n. See A000069 for odious numbers.

1, 3, 1, 7, 1, 3, 8, 15, 1, 3, 12, 7, 14, 24, 1, 31, 1, 3, 20, 7, 29, 36, 1, 15, 26, 42, 1, 56, 1, 3, 32, 63, 12, 3, 43, 7, 38, 60, 14, 15, 42, 87, 1, 84, 1, 3, 48, 31, 57, 78, 1, 98, 1, 3, 67, 120, 20, 3, 60, 7, 62, 96, 29, 127, 14, 36, 68, 7, 70, 129, 1, 15

Offset: 1

Author

Vladimir Shevelev, Oct 25 2013

Keywords

• nonn
• base

Comments

Sum of evil divisors of n is A000203(n) - a(n) = A260934(n). See A001969 for evil numbers.

Links

• Peter J. C. Moses, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000203, A227872, A000069, A001969, A212302, A260934, A010060, A102392.

Programs

Maple

A227873 := proc(n)
    option remember ;
    local a,d ;
    a := 0 ;
    for d in numtheory[divisors](n) do
        if not isA001969(d) then
            a := a+d ;
        end if;
    end do:
    a ;
end proc:
seq(A227873(n),n=1..200) ; # R. J. Mathar, Aug 17 2022

Mathematica

Total[Select[Divisors@ #, OddQ@ First@ DigitCount[#, 2] &]] & /@ Range@ 72 (* Michael De Vlieger, Aug 04 2015 *)

PARI

a(n) = sumdiv(n, d, d*(hammingweight(d) % 2)); \\ Michel Marcus, Aug 04 2015

Formula

a(n) = Sum_{d|n} A102392(d). - Ridouane Oudra, Apr 19 2025

Extensions

More terms from Peter J. C. Moses

Minor changes. - Wolfdieter Lang, Aug 23 2015