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 Th77:
  7 divides a|^(6*n+1) - a
  proof
    6+1 divides a|^(6*n+1) - a by NAT_4:26,Th73;
    hence thesis;
  end;
