Some decomposition formulas of generalized hypergeometric functions and   formulas of an analytic continuation of the Clausen function
  In this paper, using similar symbolical method of Burchnall and Chaundy formulas of expansion for the generalized hypergeometric function were constructed. By means of the found formulas of expansion the formulas of an analytic continuation for hypergeometric function of Clausen is defined. The obtained formulas of an analytic continuation express known hypergeometric Appell function $ F_2 ({a;b_1, b_2 ;c_1, c_2 ;x,y}) $ which theory is well studied. 
A.Hasanov