I have searched the internet for an exact answer and although I have found many decimal approximations, https://www.wolframalpha.com/input/?i=integrate+x%5E(-x)+from+0+to+infinity I have not been able to find an exact form.
closed as off-topic by Andrés E. Caicedo, Alexandre Eremenko, Emil Jeřábek, Steven Landsburg, Nik Weaver Jun 12 at 14:16
This question appears to be off-topic. The users who voted to close gave this specific reason:
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