reserve X for set;
reserve a,b,c,k,m,n for Nat;
reserve i,j for Integer;
reserve r for Real;
reserve p,p1,p2 for Prime;

theorem Th18:
  n divides 82 implies n = 1 or n = 2 or n = 41 or n = 82
  proof
    82 = 2*41;
    hence thesis by Lem2,XPRIMES1:2,41;
  end;
