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

theorem Th26:
  2 satisfies_Sierpinski_problem_121_for 3
  proof
    set n = 2;
    thus 3 * 2|^(2|^n) + 1 is composite by Lm2,Lm4,XPRIMES0:49;
    let m be positive Nat;
    assume m < n;
    then per cases by NAT_1:23;
    suppose m = 0;
      hence thesis;
    end;
    suppose m = 1;
      hence thesis by Lm2,XPRIMES1:13;
    end;
  end;
