A334071 Decimal expansion of Sum_{k >= 1} 2^(-phi(k)), where phi is the Euler totient function (A000010).

2, 0, 8, 5, 5, 6, 1, 8, 8, 2, 5, 9, 7, 4, 1, 4, 6, 5, 2, 6, 3, 0, 3, 8, 7, 0, 8, 3, 2, 8, 4, 7, 4, 7, 5, 6, 1, 6, 1, 2, 1, 0, 7, 7, 6, 0, 3, 2, 3, 8, 7, 3, 7, 1, 9, 4, 7, 5, 7, 9, 3, 8, 8, 3, 1, 3, 6, 1, 8, 0, 1, 3, 3, 7, 1, 0, 5, 8, 8, 2, 1, 7, 1, 0, 3, 1, 9

Offset

1,1

Comments

This constant is irrational (Erdős and Graham, 1980).

Links

Table of n, a(n) for n=1..87.

Paul Erdős and Ronald L. Graham, Old and new problems and results in combinatorial number theory, L'enseignement Mathématique, Université de Genève, 1980.

Example

2.08556188259741465263038708328474756161210776032387...

Mathematica

RealDigits[Sum[2^(-EulerPhi[n]), {n, 1, 2000}], 10, 100][[1]]

Prog

(PARI) suminf(k=1, 1/2^eulerphi(k)) \\ Michel Marcus, Apr 14 2020

Crossrefs

Cf. A000010, A334072.

Sequence in context: A185348 A321599 A020780 * A243406 A293934 A356651

Adjacent sequences: A334068 A334069 A334070 * A334072 A334073 A334074

Keyword

nonn,cons

Author

Amiram Eldar, Apr 13 2020

Status

approved