FUNCTION ack(m, n)
    IF m = 0 THEN LET ack = n+1
    IF m > 0 AND n = 0 THEN LET ack = ack(m-1, 1)
    IF m > 0 AND n > 0 THEN LET ack = ack(m-1, ack(m, n-1))
END FUNCTION

FOR m = 0 TO 4
    PRINT USING "###": m;
    FOR n = 0 TO 8
        ! A(4, 1) OR higher will RUN OUT of stack memory (default 1M)
        ! change n = 1 TO n = 2 TO calculate A(4, 2), increase stack!
        IF m = 4 AND n = 1 THEN EXIT FOR
        PRINT USING "######": ack(m, n);
    NEXT n
    PRINT
NEXT m

END