OFFSET
1,2
COMMENTS
The corresponding quotients A306070(m)/m are 1, 1, 57, 418, ... (see the link for more values).
a(22) > 6.5*10^8, if it exists.
LINKS
MATHEMATICA
phi[x_, n_] := DivisorSum[n, MoebiusMu[#]*Floor[x/#] &]; bphi[n_] := DivisorSum[n, (-1)^PrimeNu[#]*phi[n/#, #] &, CoprimeQ[#, n/#] &]; seq = {}; s = 0; Do[s = s + bphi[n]; If[Divisible[s, n], AppendTo[seq, n]], {n, 1, 10^6}]; seq
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Aug 25 2022
STATUS
approved