theorem Th35:
  for i1,i2,i3 holds
    {p: p.i3 = Product (1+((p.i1) * idseq (p.i2))) & p.i1 >= 1}
  is diophantine Subset of n -xtuples_of NAT
proof
  let i1,i2,i3;set n12=n+13;
  defpred R[XFinSequence of NAT] means
    $1.i3 = Product (1+(($1.i1) * idseq ($1.i2))) & $1.i1 >= 1;
  set RR = {p: R[p] };
  per cases;
  suppose A1:n=0;
    RR c= n -xtuples_of NAT
    proof
      let x be object;
      assume x in RR;
      then ex p be n-element XFinSequence of NAT st
      x= p & R[p];
      hence thesis by HILB10_2:def 5;
    end;
    hence thesis by A1;
  end;
  suppose n<>0;
    hence thesis by Th34;
  end;
end;
