OFFSET
1,2
COMMENTS
FORMULA
The triple integral is most conveniently estimated from the identity Integral_{z = 0..1} Integral_{y = 0..1} Integral_{x = 0..1} 1/(x*y*z)^(x*y*z) dx dy dz = 1/2*Sum_{n = 1..oo} (1/n^n + 1/n^(n+1)).
EXAMPLE
1.21483799601716270069...
MATHEMATICA
digits = 103; 1/2*NSum[ (1/n^n + 1/n^(n+1)), {n, 1, Infinity}, WorkingPrecision -> digits+10, NSumTerms -> 100] // RealDigits[#, 10, digits]& // First (* Jean-François Alcover, Feb 15 2013, from formula *)
PROG
(PARI) default( realprecision, 105); v = Vec( Str( suminf( n=1, n^-n + n^-(n+1)) / 20)); for( n=3, 105, print1( v[n], ", ")); /* Michael Somos, Mar 07 2012 */
CROSSREFS
KEYWORD
AUTHOR
Peter Bala, Mar 04 2012
STATUS
approved