OFFSET
1,2
COMMENTS
Equivalently, numbers k such that k | A113184(k).
The corresponding ratios A002129(k)/k are 1, -2, -2, -3, -2, -3, -3, -4, -4, -4, -4, -4, -4, -4, -3, -4, -4, -3, -2, -4, ...
LINKS
EXAMPLE
60 is a term since A002129(60) = -120 is divisible by 60.
MATHEMATICA
f[p_, e_] := If[p == 2, 2^(e + 1)-3, (p^(e + 1) - 1)/(p - 1)]; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; Select[Range[10^5], Divisible[s[#], #] &]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Oct 24 2021
EXTENSIONS
a(20) from Martin Ehrenstein, Nov 06 2021
STATUS
approved