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 A257263 #13 Feb 14 2024 01:05:29
%S A257263 5,10,11,13,14,15,17,28,29,34,35,36,37,38,39,40,41,49,50,51,53,54,55,
%T A257263 56,57,58,59,61,62,63,65,101,106,107,109,110,111,113,124,125,130,131,
%U A257263 132,133,134,135,136,137,148,149,154,155,156,157,158,159,160,161,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,220
%N A257263 Numbers such that the least missing nonzero digit (A257079) in their factorial base representation is 3.
%H A257263 Antti Karttunen, <a href="/A257263/b257263.txt">Table of n, a(n) for n = 1..10920</a>
%H A257263 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a>.
%e A257263 The factorial base representation (A007623) of 5 is "21", the least nonzero digit missing is 3, thus 5 is included.
%e A257263 The f.b.r. of 10 is "120", and likewise, 3 is the least missing digit, thus 10 is included.
%e A257263 The f.b.r. of 101 is "4021", where the least missing digit is 3, thus 101 is included in the sequence.
%t A257263 q[n_] := Module[{k = n, m = 2, r, s = {}}, While[{k, r} = QuotientRemainder[k, m]; k != 0|| r != 0, AppendTo[s, r]; m++]; SubsetQ[s, {1, 2}] && !MemberQ[s, 3]]; Select[Range[220], q] (* _Amiram Eldar_, Feb 14 2024 *)
%o A257263 (Scheme, with _Antti Karttunen_'s IntSeq-library)
%o A257263 (define A257263 (MATCHING-POS 1 0 (lambda (n) (= 3 (A257079 n)))))
%Y A257263 Cf. A007623, A257079, A255411, A257262.
%Y A257263 Subsequence of A256450.
%K A257263 nonn,base
%O A257263 1,1
%A A257263 _Antti Karttunen_, Apr 27 2015