theorem
  p*p <= k < 3721 implies
  p = 2 or p = 3 or p = 5 or p = 7 or p = 11 or p = 13 or p = 17 or p = 19 or
  p = 23 or p = 29 or p = 31 or p = 37 or p = 41 or p = 43 or p = 47 or p = 53
  or p = 59
  proof
    assume p*p <= k < 3721;
    then p*p < 61*61 by XXREAL_0:2;
    hence thesis by Th33,NAT_4:1;
  end;
