ackermann(0..3, 4)

swampyankee: ok
ikegami:     ok

Benchmark: timing 1000 iterations of ikegami, swampyankee...
   ikegami:  6 wallclock secs ( 4.54 usr +  0.00 sys =  4.54 CPU) @ 220.46/s (n=1000)
swampyankee: 49 wallclock secs (35.96 usr +  0.02 sys = 35.98 CPU) @ 27.79/s (n=1000)

              Rate swampyankee     ikegami
swampyankee 26.8/s          --        -88%
ikegami      220/s        724%          --