
theorem
  primenumber 5 = 13
  proof
    2,3,5,7,11 are_mutually_distinct by ZFMISC_1:def 7;
    then 5 = card SetPrimenumber 13 by LS13,CARD_2:63;
    hence thesis by NAT_4:28,NEWTON:def 8;
  end;
