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Carolyn Beck

Carolyn Beck

Answered question

2022-06-08

Does n = 2 ( 1 ) n ln ( n ) have a closed form?

Answer & Explanation

stigliy0

stigliy0

Beginner2022-06-09Added 21 answers

Consider the series
Then
f ( x ) = n = 1 ( 1 ) n n x + 1 = 1 η ( x ) = 1 + ( 2 1 + x 1 ) ζ ( x )
where η and ζ are the Dirchlet eta and Riemann zeta functions, respectively. Then the summation is given by
f ( 0 ) = 0 1 η ( x ) d x = 0 1 η ( x ) d x 0.9243
Carolyn Beck

Carolyn Beck

Beginner2022-06-10Added 8 answers

Use the polyogarithm
Li s ( z ) = k = 1 z k k s , | z | < 1 .
Compare this to
n s n Li s ( z ) = k = 1 z k ( log k ) n k s n s n Li s ( z ) | s = 0 = k = 1 z k ( log k ) n

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