The On-Line Encyclopedia of Integer Sequences (OEIS)

A209059 revision #12

A209059

Decimal expansion of the triple integral Integral_{z = 0..1} Integral_{y = 0..1} Integral_{x = 0..1} (x*y*z)^(x*y*z) dx dy dz.

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

(list; constant; graph; refs; listen; history; text; internal format)

OFFSET

0,1

COMMENTS

The double integral Integral_{y = 0..1} Integral_{x = 0..1} (x*y)^(x*y) dx dy equals Integral_{x = 0..1} x^x dx, which is listed as A083648.

LINKS

Table of n, a(n) for n=0..102.

FORMULA

The triple integral is most conveniently estimated from the identity Integral_{z = 0..1} Integral_{y = 0..1} Integral_{z = 0..1} (x*y*z)^(x*y*z) dx dy dz = (1/2)*Sum_{n >= 1} (-1)^(n+1)*(1/n^n + 1/n^(n+1)).

EXAMPLE

0.83493011063622359351...

MATHEMATICA

digits = 103; 1/2*NSum[ (-1)^(n+1)*(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 *)

CROSSREFS

Cf. A073009, A083648, A209060.

Sequence in context: A334064 A021549 A013665 * A202779 A328498 A199440

Adjacent sequences: A209056 A209057 A209058 * A209060 A209061 A209062

KEYWORD

nonn,easy,cons

AUTHOR

Peter Bala, Mar 04 2012

STATUS

editing