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;

theorem
  k>1 implies not k divides (k+1)|^n
  proof
    assume k>1; then
    not k divides 1|^n by NAT_D:7;
    hence thesis by Th11;
  end;
