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Qiaochu Yuan
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Let $a_k$ be the integral. Then

$$\sum_{k \ge 0} \frac{a_k}{k!} t^k = \int_1^{\infty} \frac{ \{ u \} }{u^2} e^{t \log u} \, du = \int_1^{\infty} \{ u \} u^{t-2} \, du = \frac{1 - \zeta(1 - t) - \frac{1}{t}}{1 - t}.$$

(Generating functions are good for more than combinatorics!)

Qiaochu Yuan
  • 118.2k
  • 40
  • 447
  • 741