Listened to a good traditional heavy metal album called "Satan's Hallow" by Satan's Hallow. But they almost copied a Rainbow's song then stopped listening
I guess norm idea won't work. If we let $x_j = (1/j,\frac{1}{2},\ldots,\frac{1}{j},\frac{1}{j},\ldots)$, then we have $f(x_j) = (\frac{1}{j},\frac{1}{2j},\ldots)$
@TedShifrin The very original proof of Riesz brother's theorem : If $\mu$(Borel measure on $[-pi,pi]$) is of analytic type, then it is absolutely continuous wrt Lebesgue measure, uses such construction.