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Search: id:A072173
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A072173 (2*n+1)*239^(2*n+1). +0
2
239, 40955757, 3899056325995, 311805194956024553, 22899374409963958061031, 1598709646931895970271741029, 107923510786468980575690686466147, 7113114068808339968612339655730133985, 460482613887654678993386180604955781138143, 29397724727626925615108413436728112018437968221 (list; graph; listen)
OFFSET

0,1

COMMENT

J. Machin (died 1751) used Pi/4 = 4*Sum_{n=0..inf} (-1)^n/((2*n+1)*5^(2*n+1)) - Sum_{n=0..inf} (-1)^n/((2*n+1)*239^(2*n+1)) to calculate Pi to 100 decimal places.

REFERENCES

H. Doerrie, 100 Great Problems of Elementary Mathematics, Dover, NY, 1965, p. 73

CROSSREFS

Cf. A072172.

Adjacent sequences: A072170 A072171 A072172 this_sequence A072174 A072175 A072176

Sequence in context: A065750 A056095 A069364 this_sequence A015161 A078151 A100748

KEYWORD

nonn

AUTHOR

njas, Jun 30 2002

page 1

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Last modified October 13 20:18 EDT 2008. Contains 145016 sequences.


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