Where 5^n occurs in n-almost-primes, starting at a(0)=1.

Terms

a(0) =1a(1) =3a(2) =9a(3) =30a(4) =90a(5) =269a(6) =788a(7) =2249a(8) =6340a(9) =17526a(10) =47911a(11) =129639a(12) =348251a(13) =929714a(14) =2469499a(15) =6532869a(16) =17219031a(17) =45246630a(18) =118572805a(19) =309998131a(20) =808746993a(21) =2105893899a(22) =5474080107a(23) =14207001052a(24) =36818679828a(25) =95292132897a(26) =246327403310