26480

with the numbers 1-5 all the numbers that can possibly go at the bottom are odd e.g. 4 1
2 5
3
with the numbers 2-6 however all hte numbers that can possibly go at the bottom are even e.g. 4 3
5 6
2

so to conclude i think that on all magic letters if the first number in the number sequence that you are using is even then the bottom number the one that is on both arms will be even and the opposite for odd.