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 A355299 #19 Jun 30 2022 08:39:13 %S A355299 1,11,7,173,10111,312211,13112221,2909,5578070441,489923144699, %T A355299 76572179303098543109,244020609982169, %U A355299 46889682313579293049990557739475858123,213414262009265690085197238570402233414850657035591,323082514382425741194809828536919444925509282219 %N A355299 Largest prime factor of n-th term in Look and Say sequence A005150, with a(1)=1. %C A355299 The terms in A005150 that are known to be primes are a(2) = 11, a(6) = 312211 and a(7) = 13112221 (A100108). %C A355299 The corresponding smallest prime factor is A334132(n). %H A355299 Wikipedia, <a href="http://en.wikipedia.org/wiki/Look-and-say_sequence">Look-and-say sequence</a>. %F A355299 a(n) = A006530(A005150(n)). %e A355299 A005150(7) = 13112221 is prime and a(7) = 13112221. %e A355299 A005150(8) = 1113213211 = 11 * 19 * 1831 * 2909, hence a(8) = 2909. %Y A355299 Cf. A005150, A006530, A079562, A100108, A334132. %K A355299 nonn,base %O A355299 1,2 %A A355299 _Bernard Schott_, Jun 27 2022