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 A046295 #19 Oct 14 2019 04:29:06
%S A046295 109,135,192,209,221,223,231,241,259,266,277,283,285,293,302,305,309,
%T A046295 314,323,333,344,345,359,382,387,400,402,407,409,413,415,421,431,443,
%U A046295 451,472,476,485,501,509,526,529,537,540,548,551,556,561,566,573,574
%N A046295 Numbers k such that 2^k contains 2^9=512 as its largest proper substring of the form 2^m.
%e A046295 2^135 = 435561429658801233233119497{512}66331066368.
%t A046295 sub2[n_] := Block[{s = ToString[2^n], k = n - 1}, While[k >= 0 && ! StringContainsQ[s, ToString[2^k]], k--]; k]; Select[Range[574], sub2[#] == 9 &] (* _Giovanni Resta_, Oct 14 2019 *)
%Y A046295 Cf. A033921.
%K A046295 nonn,base
%O A046295 1,1
%A A046295 _Patrick De Geest_, Jun 15 1998