isabelle/valid/mathd_numbertheory_461.thy (13 lines of code) (raw):
(*
Authors: Wenda Li
*)
theory mathd_numbertheory_461
imports Complex_Main "HOL-Computational_Algebra.Computational_Algebra"
"HOL-Number_Theory.Number_Theory"
begin
theorem mathd_numbertheory_461:
fixes n :: nat
assumes "n = card {k::nat. gcd k 8 = 1 \<and> 1\<le>k \<and> k < 8}"
shows "(3^n) mod 8 = (1::nat)"
sorry
end