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 A032913 #23 Oct 13 2023 14:03:08
%S A032913 1,3,7,9,19,21,43,45,55,57,115,117,127,129,259,261,271,273,331,333,
%T A032913 343,345,691,693,703,705,763,765,775,777,1555,1557,1567,1569,1627,
%U A032913 1629,1639,1641,1987,1989,1999,2001,2059,2061,2071,2073
%N A032913 Numbers whose set of base-6 digits is {1,3}.
%H A032913 Vincenzo Librandi, <a href="/A032913/b032913.txt">Table of n, a(n) for n = 1..1000</a>
%t A032913 Flatten[Table[FromDigits[#,6]&/@Tuples[{1,3},n],{n,5}]] (* _Harvey P. Dale_, Nov 16 2011 *)
%o A032913 (Magma) [n: n in [1..2500] | Set(IntegerToSequence(n, 6)) subset {1, 3}]; // _Vincenzo Librandi_, Jun 01 2012
%o A032913 (Python)
%o A032913 def A032913(n): return (int(bin(m:=n+1)[3:],6)<<1) + (6**(m.bit_length()-1)-1)//5 # _Chai Wah Wu_, Oct 13 2023
%Y A032913 Cf. A007092, A032917.
%K A032913 nonn,base
%O A032913 1,2
%A A032913 _Clark Kimberling_