OFFSET
1,1
COMMENTS
This purely mathematical constant turns up when in physics one derives Wien's displacement law from the Planck black-body radiation law (see link).
Positive solution to x = 5*(1-exp(-x)). More comments in A256500. - Stanislav Sykora, Apr 01 2015
LINKS
Stanislav Sykora, Table of n, a(n) for n = 1..2000
NIST, Wien displacement law constant, in Fundamental Physical Constants.
Eric Weisstein's World of Physics, Wien's Displacement Law
Wikipedia, Planck's law
FORMULA
u = 5 + W(-5*exp(-5)), where W() is Lambert's W-function.
EXAMPLE
u=4.965114231744276...
MATHEMATICA
RealDigits[5 + ProductLog[ -5/E^5], 10, 120][[1]] (* Robert G. Wilson v, May 04 2004 *)
PROG
(PARI) a5=solve(x=0.1, 10, x-5*(1-exp(-x))) \\ Use real precision in excess
CROSSREFS
KEYWORD
cons,nonn
AUTHOR
Jeppe Stig Nielsen, May 01 2004
EXTENSIONS
More terms from Robert G. Wilson v, May 04 2004
STATUS
approved