RosettaCodeData/Task/Ackermann-function/Yabasic/ackermann-function-1.basic

sub ack(M,N)
    if M = 0 return N + 1
    if N = 0 return ack(M-1,1)
    return ack(M-1,ack(M, N-1))
end sub

print ack(3, 4)