(*
  Authors: Wenda Li
*)

theory mathd_algebra_76 
  imports Complex_Main "HOL-Computational_Algebra.Computational_Algebra"
begin

theorem mathd_algebra_76:
  fixes f :: "int \<Rightarrow> int"
  assumes "\<forall>n. odd n \<longrightarrow> f n = n^2"
    and "\<forall> n. even n \<longrightarrow> f n = n^2 - 4*n -1" 
  shows "f 4 = -1"
  by sorry

end