A102912 Decimal expansion of a close approximation to the Ramanujan constant.

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

Offset

18,1

Comments

First differs from Ramanujan's constant (A060295) at a(33). - Omar E. Pol, Jun 26 2012

Kontsevich & Zagier give also exp(3*log(640320)) = 2.62537412640768000... as a close approximation to the Ramanujan constant. - Jean-François Alcover, Jun 22 2015

Links

G. C. Greubel, Table of n, a(n) for n = 18..10000

M. Kontsevich and D. Zagier, Periods, Institut des Hautes Etudes Scientifiques 2001 IHES/M/01/22

Eric Weisstein's World of Mathematics, Ramanujan Constant

Formula

Equals: Real root of x^3 - 6*x^2 + 4*x - 2 = 0, being x_{real} = (6 + (3*(45 + sqrt(489)))^(1/3) + (3*(45 - sqrt(489)))^(1/3))/3 = 5.31863, evaluated as (x_{real})^24 - 24. - G. C. Greubel, Feb 15 2018

Example

262537412640768743.999999999999251123875936799800954417367910227716...

Mathematica

RealDigits[ Root[ #^3 - 6#^2 + 4# - 2 &, 1]^24 - 24, 10, 111][[1]]

Crossrefs

Cf. A060295.

Sequence in context: A221188 A220532 A060295 * A064850 A151853 A268766

Adjacent sequences: A102909 A102910 A102911 * A102913 A102914 A102915

Keyword

cons,nonn

Author

Eric W. Weisstein, Jan 17 2005

Status

approved