A348159 Indices k of records of low value in the ratios A348158(k)/k.

1, 2, 126, 1638, 2394, 8190, 139230, 155610, 2645370, 5757570, 97878690, 420302610, 1963331370, 7145144370

Offset

1,2

Comments

The maximal possible value of the ratio A348158(k)/k is 1 which occurs at the terms of A326835.

The rounded values of the corresponding records are 1, 0.5, 0.452, 0.445, 0.437, 0.424, 0.420, 0.409, 0.404, 0.398, 0.3933, 0.3927, 0.3885, 0.3879, ...

a(15) <= 33376633290. - David A. Corneth, Oct 04 2021

Links

Table of n, a(n) for n=1..14.

Mathematica

r[n_] := Plus @@ DeleteDuplicates @ Map[EulerPhi, Divisors[n]]/n; rm = 2; s = {}; Do[If[(r1 = r[n]) < rm, rm = r1; AppendTo[s, n]], {n, 1, 2*10^5}]; s

Prog

(PARI) f(n) = vecsum(Set(apply(eulerphi, divisors(n)))); \\ A348158
lista(nn) = {my(r=oo, x); for (i=1, nn, if ((x=f(i)/i) < r, print1(i, ", "); r = x); ); } \\ Michel Marcus, Oct 04 2021

Crossrefs

Cf. A326835, A328859, A348158.

Sequence in context: A049659 A209602 A237994 * A157070 A064070 A266993

Adjacent sequences: A348156 A348157 A348158 * A348160 A348161 A348162

Keyword

nonn,more

Author

Amiram Eldar, Oct 03 2021

Status

approved