Powers of 5: a(n) = 5^n.

Terms

a(0) =1a(1) =5a(2) =25a(3) =125a(4) =625a(5) =3125a(6) =15625a(7) =78125a(8) =390625a(9) =1953125a(10) =9765625a(11) =48828125a(12) =244140625a(13) =1220703125a(14) =6103515625a(15) =30517578125a(16) =152587890625a(17) =762939453125