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A123626 Denominators of the convergents of the continued fraction for Pi/sqrt(3) using the classical continued fraction for arctan(x). +0
2
1, 5, 102, 2970, 16450, 997220, 18268740, 37403100, 2539082700, 23305436, 141249408300, 97836438700 (list; graph; listen)
OFFSET

1,2

COMMENT

It turns out that A123625(n)/a(n) are good approximations to Pi/sqrt(3). In a similar vein R. Apery discovered in 1978 a infinite sequence of good quality approximations to Pi^2. But for Pi itself, it was not until 1993 that hata succeeded in doing so!

REFERENCES

Frits Beukers, A rational approach to Pi, NAW 5/1 nr.4, december 2000, p. 378

FORMULA

Convergents are given by Pi/sqrt(3)=2/(1+p_1/(3+p_2/(5+p_3/(7+p_4/(9+...)))) where p_i=i^2/3

CROSSREFS

Cf. A123625.

Adjacent sequences: A123623 A123624 A123625 this_sequence A123627 A123628 A123629

Sequence in context: A113073 A057207 A124986 this_sequence A052138 A007619 A057016

KEYWORD

frac,nonn

AUTHOR

Benoit Cloitre (abmt(AT)orange.fr), Oct 03 2006

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Last modified May 16 23:01 EDT 2008. Contains 139884 sequences.


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