f(1)=3,f(n)=[f(n-1)]^2

Question

write the first 4 terms of the sequence defined by the given rule. i know the answer is "3,9,81,6561" but i wanna know how you solve it.

Answer 1

an = previous term squared

sqr3, 3, 9, 81, 6561, ..

a1 = 3 = (sqr3)^2

a2 = 9 = 3^2

a3 = 81 = 9^2

a4 = 81^2 = 6561

a5 = 6561^2 =43,046,721

an with n>2 all = a number whose last digit = 1