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 A305989 #28 Sep 27 2018 11:11:11
%S A305989 0,1,1,11,1,101,11,111,1,1001,101,1101,11,1011,111,1111,1,10001,1001,
%T A305989 11001,101,10101,1101,11101,11,10011,1011,11011,111,10111,1111,11111,
%U A305989 1,100001,10001,110001,1001,101001,11001,111001,101,100101,10101,110101,1101,101101,11101,111101,11,100011,10011
%N A305989 Numbers in binary reversed.
%H A305989 David F. Marrs, <a href="/A305989/b305989.txt">Table of n, a(n) for n = 0..10000</a>
%F A305989 a(n) = A004086(A007088(n)).
%e A305989 11 is 1011 in binary, and reversing it gives 1101 = a(11).
%p A305989 a:= n-> parse(cat(convert(n, base, 2)[])):
%p A305989 seq(a(n), n=0..75); # _Alois P. Heinz_, Jun 17 2018
%t A305989 Table[FromDigits@ Reverse@ IntegerDigits[n, 2], {n, 0, 50}]
%o A305989 (PARI) a(n) = fromdigits(Vecrev(digits(n, 2)), 10);
%o A305989 (Python) print(0)
%o A305989 for i in range(1,50):
%o A305989 print(format(i, 'b')[::-1].strip("0"))
%Y A305989 Cf. A305877, A004086, A007088, A030101.
%K A305989 nonn,base,easy
%O A305989 0,4
%A A305989 _David F. Marrs_, Jun 16 2018