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A019692
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Decimal expansion of 2*Pi.
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17
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6, 2, 8, 3, 1, 8, 5, 3, 0, 7, 1, 7, 9, 5, 8, 6, 4, 7, 6, 9, 2, 5, 2, 8, 6, 7, 6, 6, 5, 5, 9, 0, 0, 5, 7, 6, 8, 3, 9, 4, 3, 3, 8, 7, 9, 8, 7, 5, 0, 2, 1, 1, 6, 4, 1, 9, 4, 9, 8, 8, 9, 1, 8, 4, 6, 1, 5, 6, 3, 2, 8, 1, 2, 5, 7, 2, 4, 1, 7, 9, 9, 7, 2, 5, 6, 0, 6, 9, 6, 5, 0, 6, 8, 4, 2, 3, 4, 1, 3
(list; constant; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| pi/5 or 2*pi/10 is the expected surface area containing completely a Brownian curve (trajectory) on plane. - Lekraj Beedassy (blekraj(AT)yahoo.com), Jul 28 2005
Bob Palais considers this a more fundamental constant that pi. As noted in the last page of the pdf, he suggests calling the alternate constant 2 pi =6.283... '1 turn', so that 90 degrees is 'a quarter turn', just as we would say in natural language. The main point is that the historical choice of the value of pi obscures the benefit of radian measure. It is easy to see that 1/4 turn is more natural than 90 degrees, but pi/2 seems almost as arbitrary. It is apparent that we can't eliminate pi but it is to be aware of its pitfalls, and introduce an alternative for those who might wish to use one. [From Jonathan Vos Post (jvospost3(AT)gmail.com), Sep 10 2010]
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REFERENCES
| "Pi is wrong!", Bob Palais, The Mathematical Intelligencer Springer-Verlag New York Volume 23, Number 3, 2001, pp. 7-8. [From Jonathan Vos Post (jvospost3(AT)gmail.com), Sep 10 2010]
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LINKS
| Harry J. Smith, Table of n, a(n) for n = 1..20000
C. Garban & J. A. T. Ferreras, The expected area of the filled planar Brownian loop is pi/5
Bob Palais, web page about "Pi is wrong!".
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EXAMPLE
| 6.283185307179586476925286766559005768394338798750211641949889184615632...
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MATHEMATICA
| RealDigits[N[Pi/5, 6! ]] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 02 2009]
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PROG
| (PARI) { default(realprecision, 20080); x=2*Pi; for (n=1, 20000, d=floor(x); x=(x-d)*10; write("b019692.txt", n, " ", d)); } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), May 31 2009]
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CROSSREFS
| Cf. A058291 Continued fraction.
Sequence in context: A021090 A177889 A086744 * A031259 A059629 A082577
Adjacent sequences: A019689 A019690 A019691 * A019693 A019694 A019695
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KEYWORD
| nonn,cons
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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