Re: [math-fun] period of fibonacci sequence mod n

If we merely ask that period>=5*n, that happens for n=10,50,250,1250,6250,31250, and which all are of form 2*5^k, but for no other n up to 270000. Note in particular that n=156250=2*5^7 is NOT listed. In all six of these cases, the period equals 6*n.

--that's funny. Rerunning my program, this time it said n=156250 obeyed the rule (?hardware bug?), and indeed it claims the rule works for each n=2*5^k for k=1,2,3,4,5,6,7,8,9,10,11.