a(n) is the smallest k > 6 such that k is a Niven number at least in all the bases from 1 to n.

Terms

a(0) =7a(1) =8a(2) =8a(3) =8a(4) =8a(5) =12a(6) =12a(7) =24a(8) =24a(9) =24a(10) =24a(11) =24a(12) =24a(13) =432a(14) =720a(15) =720a(16) =720a(17) =720a(18) =720a(19) =840a(20) =840a(21) =840a(22) =3360a(23) =13860a(24) =13860a(25) =13860a(26) =13860a(27) =13860a(28) =40320a(29) =100800