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 A004751 #29 Apr 30 2021 16:29:19
%S A004751 9,17,18,19,25,33,34,35,36,37,38,39,41,49,50,51,57,65,66,67,68,69,70,
%T A004751 71,72,73,74,75,76,77,78,79,81,82,83,89,97,98,99,100,101,102,103,105,
%U A004751 113,114,115,121,129,130,131,132,133,134,135,136,137,138,139
%N A004751 Binary expansion contains 001.
%H A004751 Indranil Ghosh, <a href="/A004751/b004751.txt">Table of n, a(n) for n = 1..32769</a>
%H A004751 <a href="/index/Ar#2-automatic">Index entries for 2-automatic sequences</a>.
%F A004751 a(n) ~ n. - _Charles R Greathouse IV_, Oct 23 2015
%e A004751 19 is in the sequence because 19 = 10011_2 and '10011' has '001' as one of its substrings. - _Indranil Ghosh_, Feb 11 2017
%t A004751 Select[Range@ 139, Length@ SequencePosition[IntegerDigits[#, 2], {0, 0, 1}] > 0 &] (* Version 10.1, or *)
%t A004751 Select[Range@ 139, MemberQ[Partition[IntegerDigits[#, 2], 3, 1], {0, 0, 1}] &] (* _Michael De Vlieger_, Feb 11 2017 *)
%t A004751 Select[Range[150],SequenceCount[IntegerDigits[#,2],{0,0,1}]>0&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jun 15 2018 *)
%o A004751 (Python)
%o A004751 i=j=0
%o A004751 while j<=100:
%o A004751 if "001" in bin(i)[2:]:
%o A004751 print(str(j)+" "+str(i))
%o A004751 j+=1
%o A004751 i+=1 # _Indranil Ghosh_, Feb 11 2017
%o A004751 (PARI) is(n)=while(n>8, if(bitand(n,7)==1, return(1)); n>>=1); 0 \\ _Charles R Greathouse IV_, Feb 11 2017
%Y A004751 Cf. A004748, A004749, A004750, A004752, A004753.
%K A004751 nonn,base,easy
%O A004751 1,1
%A A004751 _N. J. A. Sloane_
%E A004751 Offset corrected by _Charles R Greathouse IV_, Feb 11 2017