

A006890


Decimal expansion of Feigenbaum bifurcation velocity.
(Formerly M3264)


15



4, 6, 6, 9, 2, 0, 1, 6, 0, 9, 1, 0, 2, 9, 9, 0, 6, 7, 1, 8, 5, 3, 2, 0, 3, 8, 2, 0, 4, 6, 6, 2, 0, 1, 6, 1, 7, 2, 5, 8, 1, 8, 5, 5, 7, 7, 4, 7, 5, 7, 6, 8, 6, 3, 2, 7, 4, 5, 6, 5, 1, 3, 4, 3, 0, 0, 4, 1, 3, 4, 3, 3, 0, 2, 1, 1, 3, 1, 4, 7, 3, 7, 1, 3, 8, 6, 8, 9, 7, 4, 4, 0, 2, 3, 9, 4, 8, 0, 1, 3, 8, 1, 7, 1, 6
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OFFSET

1,1


COMMENTS

"... These are related to properties of dynamical systems with 'perioddoubling' oscillations. The ratio of successive differences between perioddoubling bifurcation parameters approaches the number 4.669... Period doubling has been discovered in many physical systems before they enter the chaotic regime. Feigenbaum numbers have not been proved to be transcendental but are generally believed to be. ..." [Pickover]
The Feigenbaum delta constant is the convergence ratio {g(k)g(k1)}/{g(k+1)g(k)} of successive perioddoubling thresholds g(k) in the continuous map x(n+1)=f(x(n),g) of an interval onto itself.  Lekraj Beedassy, Jan 07 2005
The above statement is only valid for functions f satisfying some properties, e.g., having a single locally quadratic maximum. See, e.g., the MathWorld link for more details.  M. F. Hasler, May 01 2018


REFERENCES

Michael F. Barnsley, Fractals Everywhere, New Edition, Prof. of Math., Australian National University, Dover Publications, Inc., Mineola, NY, 2012, page 314.
S. R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, pp. 6576
C. A. Pickover, (1993) 'The fifteen most famous transcendental numbers.' "Journal of Recreational Mathematics," 25(1):12.
C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," Chapter 44, 'The 15 Most Famous Transcendental Numbers,' Oxford University Press, Oxford, England, 2000, pages 103  106.
C. A. Pickover, The Math Book, Sterling, NY, 2009; see p. 462.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1019
K. Briggs, A precise calculation of the Feigenbaum constants, Math. Comp., 57 (1991), 435439.
B. Derrida, A. Gervois and Y. Pomeau, Universal metric properties of bifurcations, J. Phys. A 12 (1979), 269296.
Brady Haran and Phillip Moriarty, A magic number (video) (2009).
Brady Haran and Ben Sparks, 4.669, Numberphile video (2017).
Sibyl Kempson, Restless Eye: Text for the Advanced Beginner Group, PAJ: A Journal of Performance and Art, Volume 34, Number 3, September 2012 (PAJ 102).
A. Krowne, PlanetMath.org, Feigenbaum constant
R. Munafo, Feigenbaum Constant
C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," Zentralblatt review
Simon Plouffe, Feigenbaum constants
Simon Plouffe, Feigenbaum constants to 1018 decimal places
Eric Weisstein's World of Mathematics, Feigenbaum Constant
Eric Weisstein's World of Mathematics, Feigenbaum Constant Approximations
Wikipedia, Feigenbaum constant


EXAMPLE

4.669201609102990671853203820466201617258185577475768632745651343004134...


CROSSREFS

Cf. A159766 and A069544 (continued fraction), A069261 (Egyptian fraction), A108952 (1/delta), A102817 (Gamma(delta^2)).
Cf. A006891 (Feigenbaum reduction parameter), A218453.
Sequence in context: A305317 A049089 A028327 * A104123 A094078 A016122
Adjacent sequences: A006887 A006888 A006889 * A006891 A006892 A006893


KEYWORD

cons,nonn,nice


AUTHOR

N. J. A. Sloane, Colin Mallows, Jeffrey Shallit


EXTENSIONS

Additional comments from Robert G. Wilson v, Dec 29 2000


STATUS

approved



