a(n) is the first number with a total of exactly n 3's in the decimal digits of its divisors.

Terms

a(0) =1a(1) =3a(2) =30a(3) =33a(4) =132a(5) =333a(6) =330a(7) =660a(8) =1320a(9) =1980a(10) =2310a(11) =2772a(12) =3960a(13) =6660a(14) =6732a(15) =8190a(16) =13104a(17) =6930a(18) =18480a(19) =22176a(20) =16380a(21) =35910a(22) =13860a(23) =30030a(24) =43890a(25) =32760a(26) =27720a(27) =41580a(28) =71820a(29) =73920