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A318676
Sum of divisors of n that have an even number of prime factors (counted with multiplicity).
4
1, 1, 1, 5, 1, 7, 1, 5, 10, 11, 1, 11, 1, 15, 16, 21, 1, 16, 1, 15, 22, 23, 1, 35, 26, 27, 10, 19, 1, 32, 1, 21, 34, 35, 36, 56, 1, 39, 40, 55, 1, 42, 1, 27, 25, 47, 1, 51, 50, 36, 52, 31, 1, 70, 56, 75, 58, 59, 1, 96, 1, 63, 31, 85, 66, 62, 1, 39, 70, 60, 1, 80, 1, 75, 41, 43, 78, 72, 1, 71, 91, 83, 1, 130, 86, 87, 88, 115, 1, 131, 92, 51
OFFSET
1,4
FORMULA
a(n) = Sum_{d|n} [A008836(d) > 0]*d.
a(n) = A000203(n) - A318677(n).
For all n >= 1, a(n) >= A318674(n).
a(n) = Sum_{d|n} d*A065043(d). - Antti Karttunen, Jan 24 2024
MATHEMATICA
Array[DivisorSum[#, # &, EvenQ@ PrimeOmega@ # &] &, 92] (* Michael De Vlieger, Sep 04 2018 *)
PROG
(PARI) A318676(n) = sumdiv(n, d, (!(bigomega(d)%2))*d);
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Sep 04 2018
STATUS
approved