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 A065016 #4 Mar 31 2017 22:06:48
%S A065016 1,10,11,10,101,1011,111,10,11,10101,1011,1011,1101,10111,11101,10,
%T A065016 10001,1011,10011,10101,11111,101011,10111,1011,101,101101,11,10111,
%U A065016 11101,1011101,11111,10,111011,1010001,101111,1011,100101,1010011
%N A065016 Working in base 2, replace n with the concatenation of its prime factors (without repetition).
%t A065016 Prepend[ Table[ FromDigits[ Flatten[ IntegerDigits[ Transpose[ FactorInteger[n]] [[1]], 2]]], {n, 2, 50} ], 1]
%Y A065016 Cf. A064841.
%K A065016 base,easy,nonn
%O A065016 1,2
%A A065016 _Robert G. Wilson v_, Nov 01 2001