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A331372 Decimal expansion of Sum_{k>=1} 1/(2^k - 3). 2
3, 4, 3, 6, 7, 3, 4, 3, 3, 1, 8, 1, 7, 6, 9, 0, 1, 8, 5, 4, 4, 4, 8, 2, 8, 3, 3, 3, 8, 1, 2, 4, 1, 2, 0, 6, 1, 8, 8, 8, 0, 7, 1, 7, 6, 4, 8, 6, 7, 8, 3, 8, 4, 8, 6, 5, 1, 1, 0, 5, 9, 2, 1, 7, 4, 5, 5, 0, 0, 9, 5, 4, 1, 2, 4, 1, 8, 0, 9, 7, 4, 9, 5, 2, 6, 7, 8 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Erdős and Graham (1980) asked whether this constant is irrational, and Borwein (1991) proved that it is indeed irrational.

REFERENCES

Paul Erdős, Some of my favourite unsolved problems, in A. Baker, B. Bollobás and A. Hajnal (eds.), A tribute to Paul Erdős, Cambridge University Press, 1990, p. 470.

LINKS

Table of n, a(n) for n=0..86.

Peter B. Borwein, On the irrationality of Sigma (1/(q^n + r)), Journal of Number Theory, Vol. 37, No. 3 (1991), pp. 253-259.

Paul Erdős and Ronald L. Graham, Old and new problems and results in combinatorial number theory, L'enseignement Mathématique, Université de Genève, 1980, p. 62.

EXAMPLE

0.34367343318176901854448283338124120618880717648678...

MATHEMATICA

RealDigits[Sum[1/(2^k - 3), {k, 1, 400}], 10, 100][[1]]

PROG

(PARI) suminf(k=1, 1/(2^k - 3)) \\ Michel Marcus, May 03 2020

CROSSREFS

Cf. A036563 (2^n-3), A065442.

Sequence in context: A117892 A286098 A074372 * A049276 A101684 A061800

Adjacent sequences:  A331369 A331370 A331371 * A331373 A331374 A331375

KEYWORD

nonn,cons

AUTHOR

Amiram Eldar, May 03 2020

STATUS

approved

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Last modified October 22 01:48 EDT 2021. Contains 348160 sequences. (Running on oeis4.)