OFFSET
1,1
LINKS
MAPLE
ader:= proc(n) local F, t;
F:= ifactors(n)[2];
add(t[2]*n/t[1], t= F)
end proc:
filter:= n -> n - ader(numtheory:-sigma(n)) mod 2 = 0:
select(filter, [$1..1000]); # Robert Israel, Sep 11 2024
MATHEMATICA
ad[1] = 0; ad[n_] := n * Total@(Last[#]/First[#]& /@ FactorInteger[n]); Select[Range[157], Mod[ad[DivisorSigma[1, #]], 2] == Mod[#, 2] &] (* Amiram Eldar, Sep 18 2021 *)
CROSSREFS
Cf. also A347883.
KEYWORD
nonn
AUTHOR
Antti Karttunen, Sep 17 2021
STATUS
approved