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 A257001 #21 Dec 23 2024 14:53:44
%S A257001 18,27,36,45,54,63,72,81,96,98,108,117,126,135,144,153,162,171,180,
%T A257001 189,192,207,216,225,234,243,252,261,270,288,296,306,315,324,333,342,
%U A257001 351,360,378,387,392,405,414,423,432,441,450,468,477,486,496,504,513,522
%N A257001 Numbers such that the largest missing digit is a divisor.
%C A257001 a(n) mod A000030(A230959(a(n))) = 0.
%C A257001 Pandigital numbers are not terms: A171102, A050278.
%C A257001 The original definition used the phrase "largest absent digit".
%H A257001 Reinhard Zumkeller, <a href="/A257001/b257001.txt">Table of n, a(n) for n = 1..10000</a>
%H A257001 Éric Angelini, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2015-April/014711.html">Absent digit</a>, SeqFan list, Apr 14 2015.
%t A257001 f[x_]:=Union[Sort[IntegerDigits[x]]];
%t A257001 d={1,2,3,4,5,6,7,8,9};
%t A257001 Select[Range[525],And[f[#]!=d,Length[f[#]]<10,IntegerQ[#/Max[Complement[d,f[#]]]]]&] (* _Ivan N. Ianakiev_, Apr 14 2015 *)
%o A257001 (Haskell)
%o A257001 import Data.List ((\\)); import Data.Char (digitToInt)
%o A257001 a257001 n = a257001_list !! (n-1)
%o A257001 a257001_list = filter f [1..] where
%o A257001 f x = h > 0 && mod x h == 0 where h = a000030 $ a230959 x
%Y A257001 Cf. A000030, A230959, A050278, A116667, A171102.
%K A257001 nonn,base
%O A257001 1,1
%A A257001 _Eric Angelini_ and _Reinhard Zumkeller_, Apr 14 2015