The prime p = 5 is a factor of F_5 = 2^32 + 1? True or False, and why?
True, since 2^4≡1(mod5) and 2^32=(2^4)^8≡1, so F_5≡2(mod5)
False, 5 | F_5 because 2^32≡-1(mod5)... need 2^32+1≡0
False — actually we need 2^32+1≡0(mod5): 2^4≡1(mod5), 2^32≡1, F_5≡2(mod5), so 5∤F_5
True, 5 | F_5