A139520 - OEIS

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A139520

Denominators of an Egyptian fraction for Catalan constant, using only prime numbers and allowing repetitions.

2, 3, 13, 179, 8161, 17319373, 24288185721827, 115965508643355137277722177, 235520782452648150490328050427067627593114827790363, 34927738441197833781363566983541975805101681093066970452740268721673910282017002081858804680098723909

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

COMMENTS

Good approximation up to 789 decimal digits.

REFERENCES

Mohammad K. Azarian, Sylvester's Sequence and the Infinite Egyptian Fraction Decomposition of 1, Problem 958, College Mathematics Journal, Vol. 42, No. 4, September 2011, p. 330. Solution published in Vol. 43, No. 4, September 2012, pp. 340-342.

LINKS

Table of n, a(n) for n=0..9.

MAPLE

P:=proc(n) local a, i; a:=evalf(Catalan, 100); for i from 1 by 1 to n do if 1/ithprime(i)<a then a:=a-1/ithprime(i); print(a); print(ithprime(i)); fi; od; end: P(100000);

CROSSREFS

Cf. A139514-A139519, A139521-A139523.

Sequence in context: A113785 A118323 A113494 * A132535 A056806 A376058

Adjacent sequences: A139517 A139518 A139519 * A139521 A139522 A139523

KEYWORD

easy,nonn,frac

AUTHOR

Paolo P. Lava and Giorgio Balzarotti, Apr 28 2008

STATUS

approved