The (5^n)-th composite number.

Terms

a(0) =4a(1) =10a(2) =38a(3) =164a(4) =760a(5) =3634a(6) =17653a(7) =86542a(8) =426510a(9) =2109602a(10) =10458654a(11) =51938515a(12) =258246036a(13) =1285227649a(14) =6400837884a(15) =31896080698a(16) =159013169263a(17) =793026358830