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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 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.)