A346406 Decimal expansion of Sum_{k>=1} A000005(k)/A003418(k).

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

Offset

1,1

Comments

This constant is irrational (Erdős and Straus, 1976).

Links

Table of n, a(n) for n=1..100.

Paul Erdős and Ernst Straus, Problem 360, Pi Mu Epsilon Journal, Vol. 6, No. 5 (1976), pp. 321-323; entire issue.

Stanley Rabinowitz and Mark Bowron, Index to Mathematical Problems 1975-1979, MathPro Press, 1999. See p. 219.

Example

2.69595893238893868328430801666736896692577859631704...

Mathematica

RealDigits[Sum[DivisorSigma[0, n]/LCM @@ Range[n], {n, 1, 300}], 10, 100][[1]]

Prog

(PARI) suminf(k=1, numdiv(k)/lcm([1..k])) \\ Michel Marcus, Jul 16 2021

Crossrefs

Cf. A000005, A003418.

Sequence in context: A190407 A057052 A362533 * A078437 A372363 A235997

Adjacent sequences: A346403 A346404 A346405 * A346407 A346408 A346409

Keyword

nonn,cons

Author

Amiram Eldar, Jul 15 2021

Status

approved