A356747 - OEIS

A356747

Numbers m that divide A306070(m) = Sum_{k=1..m} bphi(k), where bphi is the bi-unitary totient function (A116550).

1, 2, 141, 1035, 2388, 3973, 5157, 14160, 37023, 68861, 99889, 116106, 117939, 627400, 1561944, 1626983, 5901444, 10054091, 12260525, 32619981, 49775099

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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

Table of n, a(n) for n=1..21.

Amiram Eldar, Table of n, a(n), A306070(a(n))/a(n) for n = 1..21.

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

Cf. A116550, A306070.

Similar sequences: A048290, A306950.

Sequence in context: A221601 A334013 A115890 * A215187 A101827 A283097

Adjacent sequences: A356744 A356745 A356746 * A356748 A356749 A356750

KEYWORD

nonn,more

AUTHOR

Amiram Eldar, Aug 25 2022

STATUS

approved