OFFSET
1,6
LINKS
FORMULA
MATHEMATICA
A318877[n_] := DivisorSum[n, # &, 2*EulerPhi[#] < # &];
Array[A318877, 100] (* Paolo Xausa, Jul 08 2024 *)
PROG
(PARI) A318877(n) = sumdiv(n, d, ((2*eulerphi(d))<d)*d);
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Sep 05 2018
STATUS
approved