r SHR3 and
   the congruential generator CONG, using addition and
   exclusive-or. Period about 2^123.
   It is one of my favorite generators.
</i></p><p>
<i>   The MWC generator concatenates two 16-bit multiply-
   with-carry generators, x(n)=36969x(n-1)+carry,
   y(n)=18000y(n-1)+carry mod 2^16, has period about
   2^60 and seems to pass all tests of randomness. A
   favorite stand-alone generator---faster than KISS,
   which contains it.
</i></p><p>
<i>   FIB is the classical Fibonacci sequence
   x(n)=x