This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A204094 #11 Mar 03 2021 12:05:37
%S A204094 0,7,70,77,700,707,770,777,7000,7007,7070,7077,7700,7707,7770,7777,
%T A204094 70000,70007,70070,70077,70700,70707,70770,70777,77000,77007,77070,
%U A204094 77077,77700,77707,77770,77777,700000,700007,700070,700077,700700,700707,700770,700777
%N A204094 Numbers whose set of base 10 digits is {0,7}.
%H A204094 Reinhard Zumkeller, <a href="/A204094/b204094.txt">Table of n, a(n) for n = 0..10000</a>
%F A204094 a(n) = 7 * A007088(n).
%t A204094 FromDigits/@Tuples[{0,7},6] (* _Harvey P. Dale_, Mar 03 2021 *)
%o A204094 (Haskell)
%o A204094 a204094 n = a204094_list !! n
%o A204094 a204094_list = map (* 7) a007088_list
%Y A204094 Cf. A078246, A169965, A169966, A169967, A169964, A204093, A204095, A097256.
%K A204094 nonn,base
%O A204094 0,2
%A A204094 _Reinhard Zumkeller_, Jan 10 2012