A021243 - OEIS

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A021243

Decimal expansion of 1/239.

0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0, 0, 4, 1, 8, 4, 1, 0

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..98.

Joerg Arndt, Arctan relations for Pi

Eric Weisstein's World of Mathematics, Machin-Like Formulas

Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 1).

FORMULA

From Jean-François Alcover, Sep 14 2015: (Start)

Pi = 16 arctan(1/5) - 4 arctan(1/239) [Machin's formula],

arctan(1/239) = arctan(1/70) - arctan(1/99) = arctan(1/408) + arctan(1/577),