reserve a,b,c,k,m,n for Nat;
reserve p for Prime;

theorem
  139 satisfies_Sierpinski_problem_76a
  proof
    let x be Nat;
    assume 139 < x < 139+10;
    then 139 < x < 148+1;
    then 139+1 <= x <= 148 by NAT_1:13;
    then x = 140 or ... or x = 148;
    hence thesis by XPRIMES0:140,141,142,143,144,145,146,147,148;
  end;
