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

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• cons
• easy

Links

• 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).

Programs

Mathematica

First[RealDigits[1/239, 10, 100, -1]] (* Paolo Xausa, Jul 28 2025 *)

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),

1/239 = 4649 / 1111111. (End)