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 A141116 #4 Mar 30 2012 17:36:44 %S A141116 2,13,101,1013,10103,101021,1010129,10101023,101010157,1010101039, %T A141116 10101010163,101010101063,1010101010131,10101010101019, %U A141116 101010101010131,1010101010101037,10101010101010141,101010101010101083 %N A141116 Smallest n-digit prime with no identical adjacent digits (or 0 if no such prime exists). %C A141116 For n >= 1, a(n) >= A056830(n), the least n-digit positive integer with no identical adjacent digits (also the least positive integer whose digits occur in n runs). Conjecture: For all n, a(n) <> 0. %C A141116 If the conjecture is true, then this sequence and the following two sequences are equivalent: i) Smallest prime with exactly n runs of digits and ii) Smallest prime with at least n runs of digits. For each n <= 625, a(n) is an n-digit prime (provided that each probable prime shown in the link is indeed a prime -- or at least one of very many (slightly) larger probable prime candidates is prime). %C A141116 As each a(n) shown is very near A056830(n), I believe it is extremely unlikely that a randomly-given n would yield a 0 term (but I don't have a proof for arbitrary n). %H A141116 Rick L. Shepherd, <a href="/A141116/b141116.txt">Table of n, a(n) for n = 1..625</a> %e A141116 a(4) = 1013 because 1013 is the smallest 4-digit prime having no identical adjacent digits; the only smaller 4-digit prime, 1009, is disqualified by the "00", identical adjacent digits (of run length 2). Also each digit, 1, 0, 1, 3, occurs in a run of identical digits of length 1 for a total of 4 runs with 1013 being the smallest prime of any length with 4 runs of digits. %Y A141116 Cf. A003617, A007809, A056830. %K A141116 base,nonn %O A141116 1,1 %A A141116 _Rick L. Shepherd_, Jun 05 2008