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A319697
Sum of even squarefree divisors of n.
4
0, 2, 0, 2, 0, 8, 0, 2, 0, 12, 0, 8, 0, 16, 0, 2, 0, 8, 0, 12, 0, 24, 0, 8, 0, 28, 0, 16, 0, 48, 0, 2, 0, 36, 0, 8, 0, 40, 0, 12, 0, 64, 0, 24, 0, 48, 0, 8, 0, 12, 0, 28, 0, 8, 0, 16, 0, 60, 0, 48, 0, 64, 0, 2, 0, 96, 0, 36, 0, 96, 0, 8, 0, 76, 0, 40, 0, 112, 0, 12, 0, 84, 0, 64, 0, 88, 0, 24, 0, 48, 0, 48, 0, 96
OFFSET
1,2
LINKS
FORMULA
a(n) = Sum_{d|n} A059841(d)*A008966(d)*d.
a(n) = A048250(n) - A206787(n).
MATHEMATICA
Table[Total[Select[Divisors[n], EvenQ[#]&&SquareFreeQ[#]&]], {n, 100}] (* Harvey P. Dale, May 18 2019 *)
f[2, e_] := 2; f[p_, e_] := p + 1; a[n_] := If[OddQ[n], 0, Times @@ f @@@ FactorInteger[n]]; Array[a, 100] (* Amiram Eldar, Jun 30 2022 *)
PROG
(PARI) A319697(n) = sumdiv(n, d, (!(d%2))*issquarefree(d)*d);
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 31 2018
STATUS
approved