Following the discovery of this and related formulas, similar formulas in other bases were investigated. This class of formulas are now known as BBP-type
formulas.
Adamchik, V. and Wagon, S. "A Simple Formula for ." Amer. Math. Monthly104,
852-855, 1997.Adamchik, V. and Wagon, S. "Pi: A 2000-Year Search
Changes Direction." http://www-2.cs.cmu.edu/~adamchik/articles/pi.htm.Bailey,
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and Moll, V. H. Experimental
Mathematics in Action. Wellesley, MA: A K Peters, p. 31, 2007.Bailey,
D. H. "A Compendium of BBP-Type Formulas for Mathematical Constants."
28 Nov 2000. http://crd.lbl.gov/~dhbailey/dhbpapers/bbp-formulas.pdf.Bailey,
D. H. "nth digit of pi" math-fun@cs.arizona.edu mailing list.
31 Oct 2002.Bailey, D. H.; Borwein, P. B.; and Plouffe, S.
"On the Rapid Computation of Various Polylogarithmic Constants." Math.
Comput.66, 903-913, 1997.Bailey, D. H.; Borwein, J. M.;
Kapoor, V.; and Weisstein, E. W. "Ten Problems in Experimental Mathematics."
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Bailey, D. Mathematics
by Experiment: Plausible Reasoning in the 21st Century. Wellesley, MA: A
K Peters, 2003.Finch, S. R. "Archimedes' Constant." §1.4
in Mathematical
Constants. Cambridge, England: Cambridge University Press, pp. 17-28,
2003.Gourdon, X. and Sebah, P. "Collection of Series for ." http://numbers.computation.free.fr/Constants/Pi/piSeries.html.Plouffe,
S. "The Story Behind a Formula for Pi." sci.math and sci.math.symbolic
newsgroup posting. 23 Jun 2003.