On a Question of Brézis and Korevaar Concerning a Class of Square-Summable Sequences
نویسندگان
چکیده
We give an elementary proof of a statement due to Brézis and Nirenberg: ∑∞ k=−∞ k|ak| is an integer whenever {ak}k=−∞ is a sequence of complex numbers such that ∑∞ k=−∞ akān+k = { 0 if n 6= 0, 1 if n = 0, for all integers n and ∑∞ k=−∞ |k| |ak| <∞.
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