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A064859 Decimal expansion of sum of reciprocals of lcm(1..n) = A003418(n). 10
1, 7, 8, 7, 7, 8, 0, 4, 5, 6, 1, 7, 2, 4, 6, 6, 5, 4, 6, 0, 6, 4, 9, 3, 4, 3, 2, 6, 0, 2, 5, 6, 6, 2, 7, 9, 4, 5, 9, 3, 9, 6, 1, 7, 4, 7, 2, 9, 6, 9, 6, 0, 8, 3, 7, 2, 5, 3, 0, 2, 6, 9, 9, 2, 9, 2, 2, 8, 9, 0, 2, 3, 5, 0, 8, 2, 2, 3, 2, 6, 1, 5, 5, 2, 8, 3, 3, 6, 8, 7, 8, 0, 8, 5, 6, 9, 7, 9, 7, 9, 9, 4, 6, 9, 5 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This constant is irrational (Erdős and Graham, 1980). - Amiram Eldar, Apr 13 2020

LINKS

Table of n, a(n) for n=1..105.

Paul Erdős and Ronald L. Graham, Old and new problems and results in combinatorial number theory, L'enseignement Mathématique, Université de Genève, 1980. See p. 65.

FORMULA

Equals Sum_{j>=1} 1/lcm(1..j).

EXAMPLE

1.7877804561724665460649343260256627945939617472969608372530269929228902350...

MATHEMATICA

f[n_] := LCM @@ Range@ n; RealDigits[Plus @@ (1/Array[f, 255]), 10, 111][[1]] (* Robert G. Wilson v, Jul 11 2011 *)

PROG

(PARI) suminf(k=1, 1/lcm(vector(k, j, j))) \\ Michel Marcus, Mar 11 2018

CROSSREFS

Cf. A003418, A064857, A064858.

Sequence in context: A154192 A011283 A179659 * A233778 A217168 A010728

Adjacent sequences:  A064856 A064857 A064858 * A064860 A064861 A064862

KEYWORD

nonn,cons

AUTHOR

Labos Elemer, Oct 08 2001

STATUS

approved

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Last modified November 28 16:34 EST 2021. Contains 349413 sequences. (Running on oeis4.)