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 A099821 #23 Apr 23 2020 04:23:11 %S A099821 1,11,101,111,1001,1011,1101,1111,10001,10011,10101,10111,11001,11011, %T A099821 11101,11111,100001,100011,100101,100111,101001,101011,101101,101111, %U A099821 110001,110011,110101,110111,111001,111011,111101,111111,1000001 %N A099821 Odd positive integers in base 2 (bisection of A007088). %C A099821 List of binary vectors that begin and end with 1. %H A099821 N. J. A. Sloane, <a href="/A099821/b099821.txt">Table of n, a(n) for n = 1..1000</a> %H A099821 <a href="/index/Ar#2-automatic">Index entries for 2-automatic sequences</a>. %p A099821 seq(convert(2*n-1,binary),n=1..37); # _Emeric Deutsch_, Dec 15 2004 %t A099821 FromDigits/@IntegerDigits[Range[1,71,2],2] (* _Harvey P. Dale_, Apr 05 2019 *) %o A099821 (PARI) a(n) = fromdigits(binary(2*n-1), 10); \\ _Michel Marcus_, Apr 23 2020 %Y A099821 Cf. A007088, A099820. %K A099821 nonn,base,easy %O A099821 1,2 %A A099821 _N. J. A. Sloane_, Nov 19 2004 %E A099821 More terms from _Emeric Deutsch_, Dec 15 2004