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%I
%S 5,375,15625,546875,17578125,537109375,15869140625,457763671875,
%T 12969970703125,362396240234375,10013580322265625,274181365966796875,
%U 7450580596923828125,201165676116943359375,5401670932769775390625,144354999065399169921875
%N (2*n+1)*5^(2*n+1).
%C 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.
%D H. Doerrie, 100 Great Problems of Elementary Mathematics, Dover, NY, 1965, p. 73
%Y Cf. A072173.
%Y Cf. A157332. [From _Jaume Oliver Lafont_, Mar 03 2009]
%K nonn
%O 0,1
%A _N. J. A. Sloane_, Jun 30 2002
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