‘The Pi Man’ by Alfred Bester
Almost, for a moment, I thought I would have to attack the conductor of the Opera Comique, but fate was kind and let me off with nothing worse than indecent exposure, and I was able to square it by founding a scholarship at the Sorbonne.
A sentence like that is worth the price of admittance alone. Our narrator is a “compensator”, providing cosmic balance against his will. He gets into some scraps. The rest of the story is fun but fun of the hectic variety which gives you a bit of a headache. As always, Bester is so much more vibrant than his contemporaries though.
It goes without saying that this isn’t hard SF and, as has so often been the case, H&K come right out and admit this: “He was pyrotechnic, self-consciously literary, artificial, and brilliant, and utterly rejected the style and affect of hard sf.” An obvious candidate for inclusion, I think you will agree.