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A021243 Decimal expansion of 1/239. 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, 0, 4, 1, 8, 4, 1, 0 (list; constant; graph; refs; listen; history; text; internal format)
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

FORMULA

a(n) = (1/49)*{13*(n mod 7)+27*[(n+1) mod 7]+34*[(n+2) mod 7]-43*[(n+3) mod 7]+27*[(n+4) mod 7]-22*[(n+5) mod 7]+6*[(n+6) mod 7]}, with n>=0. [Paolo P. Lava, Oct 05 2009]

From Jean-Fran├žois 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),

1/239 = 4649 / 1111111. (End)

CROSSREFS

Sequence in context: A263498 A198314 A105534 * A096051 A060440 A021709

Adjacent sequences:  A021240 A021241 A021242 * A021244 A021245 A021246

KEYWORD

nonn,cons

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified April 20 14:27 EDT 2019. Contains 322310 sequences. (Running on oeis4.)