For a symmetric stable process
X(t,ω) with index
α
(1,2],
f
Lp[0,2π],
p
α,
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and
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, we establish that the random Fourier–Stieltjes (RFS) series
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converges in the
mean to the stochastic integral
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, where
fβ is the fractional integral of order
β of the function
f for
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. Further it is proved that the RFS series
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is Abel summable to
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. Also we define fractional derivative of the sum
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of order
β for
an,
An(ω) as above and
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. We have shown that the formal fractional derivative of the series
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of order
β exists in the sense of
mean.