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 A225329 #21 Jan 19 2019 04:15:43 %S A225329 1,111,331,223111,222113331,332221333111,223332111333331, %T A225329 222333112331553111,332333221112223111225113331, %U A225329 223112333222331332113331222115221333111 %N A225329 Look-and-repeat: similar to look-and-say except frequency is repeated. %C A225329 Repeated frequency followed by digit-indication. Repeating the frequency allows 5 to appear, in addition to 1, 2 and 3 which are already contained in Conway's original look-and-say sequence. However, 4 still does not appear. %C A225329 The sequence is determined by triples of digits. The first two terms of a triple are the repeated figure and the last term is the digit. %C A225329 Therefore, sequences of form xy (x != y), xxyy can never appear. A fortiori, the sequence never contains series of four identical digits, but contains series of five 3, which make appear the 5's (55 and 5). However five 5's never appear. Proof: suppose it appears for the first time in a(n)-a(n+4); because of 'five five 5' in 55555, it would imply that 55555 appears form a smaller n, which is a contradiction. By the same argument, 555 also never appear. %C A225329 Also 22222 or 11111 are impossible : 22222 would imply a preceding 22yy and 11111 a preceding 1x (x != 1), but both cannot exist. %C A225329 All terms end with 1 (the seed) and, except the first two, begin with 2 or 3. %e A225329 The term after 331 is obtained by saying (repeating) two two 3, one one 1, which gives 223111. %Y A225329 Cf. A005150 (original look-and-say), A225224, A221646, A225212 (continuous look-and-say versions), A225330, A225331 (continuous look-and-repeat). %K A225329 nonn,base %O A225329 1,2 %A A225329 _Jean-Christophe Hervé_, May 12 2013