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
KEYWORD
cons,nonn
AUTHOR
Eric W. Weisstein, Jan 17 2005
STATUS
approved