OFFSET
1,6
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..20000
FORMULA
MAPLE
with(numtheory):
a:= n-> add(`if`(nops(factorset(d))::even, d, 0), d=divisors(n)):
seq(a(n), n=1..80); # Alois P. Heinz, Sep 21 2019
MATHEMATICA
a[n_] := DivisorSum[n, # &, EvenQ[PrimeNu[#]] &]; Table[a[n], {n, 1, 75}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Sep 21 2019
STATUS
approved