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 A128117 #11 Feb 09 2022 15:29:34
%S A128117 1,1,2,1,2,3,1,2,3,1,2,3,4,1,2,3,4,5,1,2,3,4,5,1,2,3,4,5,6,1,2,3,4,5,
%T A128117 6,1,2,3,4,5,6,1,2,3,4,5,6,7,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,
%U A128117 5,6,7,8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,10,1,2,3,4
%N A128117 At the n-th iteration the sequence of integers from 1 to n are appended to the sequence a(n) times.
%H A128117 Rémy Sigrist, <a href="/A128117/b128117.txt">Table of n, a(n) for n = 1..10258</a> (first 371 terms from Reed Kelly)
%e A128117 a(5) = 2 so 1,2,3,4,5,1,2,3,4,5 is added to the end of the sequence at the fifth iteration.
%t A128117 cr[n_] := Module[ { A = {1,1,2}, i, j }, For [ i = 3, i <= n, i++, A = Join[ A, Flatten[ Table[ Range[i], {A[[i]]} ]]]; ]; A ]
%o A128117 (PARI) a = vector(101, n, 1); m=0; for (n=1, 10, for (t=1, a[n], for (k=1, n, print1 (a[m++]=k", ")))) \\ _Rémy Sigrist_, Feb 09 2022
%Y A128117 Cf. A001462.
%K A128117 easy,nonn
%O A128117 1,3
%A A128117 _Reed Kelly_, Feb 15 2007