On some p-adic power series attached to the arithmetic of $\mathbb   Q(\zeta\_p).$
  In this paper, we prove that the derivative of the Iwasawa power series associated to p-adic L-functions of $\mathbb Q(\zeta\_p)$ are not divisible by p. This extends previous results obtained by Ferrero and Washington in 1979. 
Bruno Angles (LMNO)