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 Th62:
  (2*n+1)|^2 = 4*n*(n+1)+1
  proof
    thus (2*n+1)|^2 = (2*n+1)*(2*n+1) by NEWTON:81
    .= 4*n*(n+1)+1;
  end;
