reserve a,b,c,d,m,x,n,j,k,l for Nat,
  t,u,v,z for Integer,
  f,F for FinSequence of NAT;
reserve p,q,r,s for real number;
reserve a,b,c,d,m,x,n,k,l for Nat,
  t,z for Integer,
  f,F,G for FinSequence of REAL;
reserve q,r,s for real number;
reserve D for set;

theorem
  for n st n = ((a,b) In_Power (k+l)).(k+1) & l>0 holds a divides n
  proof
    let n;
    assume n = ((a,b) In_Power (k+l)).(k+1) & l>0; then
    consider x such that
    A2: n = a*x by Th50;
    thus thesis by A2;
  end;
