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A356747
Numbers m that divide A306070(m) = Sum_{k=1..m} bphi(k), where bphi is the bi-unitary totient function (A116550).
1
1, 2, 141, 1035, 2388, 3973, 5157, 14160, 37023, 68861, 99889, 116106, 117939, 627400, 1561944, 1626983, 5901444, 10054091, 12260525, 32619981, 49775099
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.
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
Similar sequences: A048290, A306950.
Sequence in context: A221601 A334013 A115890 * A215187 A101827 A283097
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Aug 25 2022
STATUS
approved