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 A090103 #13 Dec 09 2020 18:10:48
%S A090103 0,11,111,1111,11111,110,1111111,11111111,111111111,1010,11111111111,
%T A090103 1100,1111111111111,1110,1111,1111111111111111,11111111111111111,
%U A090103 10010,1111111111111111111,10100,10101,10110,11111111111111111111111,11000
%N A090103 n written in base equal to the number of distinct prime factors of n and a(1)=0.
%C A090103 All primes p are written in number-system of base one so rather long strings of 11...111 arise.
%F A090103 n in base A001221(n).
%e A090103 a(6469693230) = 6469693230.
%e A090103 Symbol A to denote "10" first appears at n = 200560490130 = A002110(11).
%t A090103 tn[x_] := Fold[nd, 0, x]; Do[s=lf[n];If[Equal[s, 1], Print[tn[Table[1, {i, 1, n}]]]]; If[ !Equal[s, 1], Print[tn[IntegerDigits[n, s]]]], {n, 2, 211}]
%Y A090103 Cf. A002110, A001221, A031974 (primes in base one).
%K A090103 base,nonn
%O A090103 1,2
%A A090103 _Labos Elemer_, Dec 16 2003