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A003417 Continued fraction for e.
(Formerly M0088)
+0
11
2, 1, 2, 1, 1, 4, 1, 1, 6, 1, 1, 8, 1, 1, 10, 1, 1, 12, 1, 1, 14, 1, 1, 16, 1, 1, 18, 1, 1, 20, 1, 1, 22, 1, 1, 24, 1, 1, 26, 1, 1, 28, 1, 1, 30, 1, 1, 32, 1, 1, 34, 1, 1, 36, 1, 1, 38, 1, 1, 40, 1, 1, 42, 1, 1, 44, 1, 1, 46, 1, 1, 48, 1, 1, 50, 1, 1, 52, 1, 1, 54, 1, 1, 56, 1, 1, 58, 1, 1, 60, 1, 1, 62, 1, 1, 64, 1, 1, 66 (list; graph; listen)
OFFSET

1,1

COMMENT

This is also the Engel expansion for 3*exp(1/2)/2 - 1/2. - Gerald McGarvey (Gerald.McGarvey(AT)comcast.net), Aug 07 2004

First differences are A120691. - Paul Barry (pbarry(AT)wit.ie), Jun 27 2006

REFERENCES

H. Cohn, A short proof of the simple continued fraction expansion of e, Amer. Math. Monthly, 113 (No. 1, 2006), 57-62.

CRC Standard Mathematical Tables and Formulae, 30th ed. 1996, p. 88.

S. R. Finch, Mathematical Constants, Cambridge, 2003, Section 1.3.2.

J. R. Goldman, The Queen of Mathematics, 1998, p. 70.

T. J. Osler, A proof of the continued fraction expansion of e^(1/M), Amer. Math. Monthly, 113 (No. 1, 2006), 62-66.

O. Perron, Die Lehre von den Kettenbr\"{u}chen, 2nd ed., Teubner, Leipzig, 1929, p. 134.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 1..10000

K. Matthews, Finding the continued fraction of e^(l/m)

S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

G. Xiao, Contfrac

Index entries for continued fractions for constants

FORMULA

G.f.: (2+x+2x^2-3x^3-x^4+x^6)/(1-2x^3+x^6); a(n)=sum{k=0..n, 2*C(0,k)-C(1,k)-2*sin(2*pi*(k-1)/3)*floor((2k-1)/3)/sqrt(3)} [offset 0]; - Paul Barry (pbarry(AT)wit.ie), Jun 27 2006

a(n)=2*a(n-3)-a(n-6), n>=8 . [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Feb 10 2009]

MAPLE

numtheory[cfrac](exp(1), 100, 'quotients'); - Jani Melik (jani_melik(AT)hotmail.com), May 25 2006

A003417:=(2+z+2*z**2-3*z**3-z**4+z**6)/(z-1)**2/(z**2+z+1)**2; [S. Plouffe in his 1992 dissertation.]

MATHEMATICA

ContinuedFraction[E, 100] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Apr 07 2006

PROGRAM

(PARI) contfrac(exp(1)-1) - Alexander R. Povolotsky (pevnev(AT)juno.com), Feb 23 2008

(PARI) { allocatemem(932245000); default(realprecision, 25000); x=contfrac(exp(1)); for (n=1, 10000, write("b003417.txt", n, " ", x[n])); } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Apr 14 2009]

CROSSREFS

Cf. A001113, A007676, A007677.

Sequence in context: A078997 A024680 A083531 this_sequence A158986 A079900 A117354

Adjacent sequences: A003414 A003415 A003416 this_sequence A003418 A003419 A003420

KEYWORD

nonn,cofr,nice,easy

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified December 2 11:54 EST 2009. Contains 167921 sequences.


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