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 A200065 #40 Apr 20 2012 11:58:49
%S A200065 0,0,13,0,0,0,17,0,19,0,1111111111111111111,0,113,0,0,0,1117,0,11119,
%T A200065 0,111121,0,1123,0,0,0,127,0,1129,0,131,0
%N A200065 Start with n, concatenate its trivial divisors, and repeat until a prime is reached. a(n) = 0 if no prime is ever reached.
%C A200065 a(33) has 715 digits and is too large to include.
%C A200065 a(A065502(n)) = 0. There are other integers for which a(n) = 0 (i.e., n = 221).
%C A200065 The number (10^270343 - 1)/9 appears 161046 times in this sequence.
%C A200065 All odd primes from A096497 are in the sequence.
%H A200065 Arkadiusz Wesolowski, <a href="/A200065/b200065.txt">Table of n, a(n) for n = 1..1032</a>
%e A200065 17 -> {1, 17} = 117 (composite) -> {1, 117} = 1117 (prime), so a(17) = 1117.
%t A200065 lst = {}; Do[If[DivisorSigma[0, n] == 1 || Divisible[n, 5] || EvenQ[n], AppendTo[lst, 0], If[PrimeQ[n], n = 10^Length[IntegerDigits[n]] + n]; While[True, If[PrimeQ[n], Break[]]; n = FromDigits[Flatten[IntegerDigits[{1, n}]]]]; AppendTo[lst, n]], {n, 32}]; lst
%Y A200065 Cf. A004022, A096497.
%K A200065 base,nonn
%O A200065 1,3
%A A200065 _Arkadiusz Wesolowski_, Apr 18 2012