Question

please help me to find the first five terms of the recursively defined sequence of this problem with steps, a1=3;an=6an-1.

Answer 1

I think you are trying to define it as

a(1) = 3
a(n) = 6 a(n-1)

so ...
a(2) = 6 a(1) = 6(3) = 18
a(3) = 6 a(2) = 6(18) = 108
a(4) = 6 a(3) = 6(108) = 648
a(5) = 6 a(4) = 6(648) = 3888