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A094640 Decimal expansion of the "alternating Euler constant" log(4/Pi). 11
2, 4, 1, 5, 6, 4, 4, 7, 5, 2, 7, 0, 4, 9, 0, 4, 4, 4, 6, 9, 1, 0, 3, 6, 8, 9, 1, 5, 6, 3, 2, 9, 4, 4, 2, 4, 5, 0, 3, 7, 0, 5, 4, 5, 5, 8, 0, 5, 1, 9, 8, 9, 3, 6, 7, 2, 7, 7, 3, 6, 9, 4, 7, 5, 1, 4, 6, 4, 9, 4, 7, 4, 0, 5, 4, 5, 6, 3, 3, 5, 1, 4, 2, 8, 1, 0, 3, 3, 8, 3, 7, 1, 7, 3, 4, 7, 6, 6, 7, 3, 8, 1, 9, 9, 3 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Decimal expansion of sum_{n>=1} (-1)^{n-1} (1/n - log(1 + 1/n)) (see Sondow 2005), so in comparison to A001620's sum formula, log(4/Pi) is an "alternating Euler constant."

REFERENCES

G. Boros and V. Moll, Irresistible Integrals: Symbolics, Analysis and Experiments in the Evaluation of Integrals, Cambridge University Press, Cambridge, 2004, Chap. 7.

J. Borwein and P. Borwein, Pi and the AGM, John Wiley & Sons, New York, 1987, Chap. 11.

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..10000

D. Huylebrouck, Similarities in irrationality proofs for Pi, ln2, zeta(2) and zeta(3), Amer. Math. Monthly 108 (2001) 222-231.

J. Sondow, Double Integrals for Euler's Constant and ln(4/Pi) and an analog of Hadjicostas's formula, Amer. Math. Monthly 112 (2005), 61-65.

J. Sondow, New Vacca-Type Rational Series for Euler's Constant and Its "Alternating" Analog ln(4/Pi), Additive Number Theory, Festschrift In Honor of the Sixtieth Birthday of Melvyn B. Nathanson (D. Chudnovsky and G. Chudnovsky, eds.), Springer, 2010, pp. 331-340.

J. Sondow and P. Hadjicostas, The generalized-Euler-constant function gamma(z) and a generalization of Somos's quadratic recurrence constant, J. Math. Anal. Appl. 332 (1) (2007), 292-314.

Eric Weisstein's World of Mathematics, Euler-Mascheroni Constant

Eric Weisstein's World of Mathematics, Hadjicostas's Formula

Eric Weisstein's World of Mathematics, Digit Count

FORMULA

Integral_{x=0..1, y=0..1} (x-1)/((1+x*y)*log(x*y)) - (see Sondow 2005).

EXAMPLE

log(4/Pi) = 0.24156447527...

MATHEMATICA

RealDigits[ Log[4/Pi], 10, 111][[1]]

PROG

(PARI) log(4/Pi) \\ Charles R Greathouse IV, Jun 06, 2011

(MAGMA) SetDefaultRealField(RealField(100)); R:= RealField(); Log(4/Pi(R)); // G. C. Greubel, Aug 28 2018

CROSSREFS

Cf. A094641, A103130, A110625, A110626.

Sequence in context: A299918 A021418 A283741 * A070937 A278437 A175036

Adjacent sequences:  A094637 A094638 A094639 * A094641 A094642 A094643

KEYWORD

cons,easy,nonn

AUTHOR

Jonathan Sondow and Robert G. Wilson v, May 18 2004

STATUS

approved

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Last modified October 22 01:38 EDT 2018. Contains 316431 sequences. (Running on oeis4.)