OFFSET
2,2
COMMENTS
Positive real numbers x < y with x^y = y^x are parameterized by (x,y) = ((1 + 1/t)^t,(1 + 1/t)^(t+1)) for t > 0. For example, t = 2 gives (x,y) = (9/4,27/8). See Sondow and Marques 2010, pp. 155-157.
(9/4)^(27/8) = (27/8)^(9/4) corresponds to (4/9)^(4/9) = (8/27)^(8/27) (see A194789) under the equivalence x^y = y^x <==> (1/x)^(1/x) = (1/y)^(1/y).
LINKS
J. Sondow and D. Marques, Algebraic and transcendental solutions of some exponential equations, Annales Mathematicae et Informaticae, 37 (2010), 151-164.
FORMULA
-((9*ProductLog(-1, -(4/9)*log(9/4)))/(4*log(9/4))), where ProductLog is the Lambert W function, simplifies to 27/8. - Jean-François Alcover, Jun 01 2015
EXAMPLE
15.438887358552583183604460013074909718871494279680272412854330453294418363...
MATHEMATICA
RealDigits[ (9/4)^(27/8), 10, 100] // First
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Jonathan Sondow, Aug 30 2011
STATUS
approved