a(n) = floor(log(5)^n).

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =6a(5) =10a(6) =17a(7) =27a(8) =45a(9) =72a(10) =116a(11) =187a(12) =302a(13) =486a(14) =782a(15) =1259a(16) =2026a(17) =3261a(18) =5249a(19) =8449a(20) =13598a(21) =21885a(22) =35223a(23) =56690a(24) =91239a(25) =146843a(26) =236336a(27) =380368a(28) =612178a(29) =985263