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 A046288 #12 Oct 14 2019 03:47:42
%S A046288 6,10,12,18,22,32,49,52,53,56,78
%N A046288 Numbers k such that 2^k contains 2^2=4 as its largest proper substring of the form 2^m (probably finite).
%t A046288 sub2[n_] := Block[{s = ToString[2^n], k = n - 1}, While[k >= 0 && ! StringContainsQ[s, ToString[2^k]], k--]; k]; Select[Range[1000], sub2[#] == 2 &] (* _Giovanni Resta_, Oct 14 2019 *)
%Y A046288 Cf. A033921.
%K A046288 nonn,base,more
%O A046288 1,1
%A A046288 _Patrick De Geest_, Jun 15 1998