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 A221369 #10 Feb 16 2025 08:33:19 %S A221369 13,113,111113,411113,311113141,311113114231141,511113214123331141142, %T A221369 511112113314121123131132233241142151, %U A221369 711312313214115321122223124331232233241142251,411412213214115221522423224125431432233241142143151153171 %N A221369 A two-digit Look-and-Say sequence starting with 13: each term summarizes the increasing two-digit substrings of the previous term. %C A221369 a(22) is the first term containing a zero; this is due to the fact that a(21) is the first term having exactly 10 occurrences of a two-digit number, namely 10 x 42. %H A221369 Reinhard Zumkeller, <a href="/A221369/b221369.txt">Table of n, a(n) for n = 0..1000</a> %H A221369 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LookandSaySequence.html">Look and Say Sequence</a> %H A221369 Wikipedia, <a href="http://en.wikipedia.org/wiki/Look-and-say_sequence">Look-and-say sequence</a> %H A221369 Reinhard Zumkeller, <a href="/A209234/a209234.hs.txt">Haskell program for two-digit Look-and-Say sequences</a> %e A221369 a(0) = 11: 1 x 13 --> a(1) = 113; %e A221369 a(1) = 113: 1 x 11 and 1 x 13 --> a(2) = 111113; %e A221369 a(2) = 111113: 4 x 11 and 1 x 13 --> a(3) = 411113; %e A221369 a(3) = 411113: 3 x 11, 1 x 13 and 1 x 41 --> a(4) = 311113141. %o A221369 (Haskell) -- See Link. %Y A221369 Cf. A005151, A047842. %Y A221369 Cf. A209234 (start=10), A209233 (start=11), A221368 (start=12), A221372 (start=19), A221373 (start=99). %K A221369 nonn,base %O A221369 0,1 %A A221369 _Reinhard Zumkeller_, Jan 13 2013