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 A128118 #6 Mar 08 2015 20:38:10
%S A128118 1,2,1,2,1,3,2,1,4,3,2,1,4,3,2,1,5,4,3,2,1,6,5,4,3,2,1,6,5,4,3,2,1,6,
%T A128118 5,4,3,2,1,7,6,5,4,3,2,1,7,6,5,4,3,2,1,8,7,6,5,4,3,2,1,9,8,7,6,5,4,3,
%U A128118 2,1,9,8,7,6,5,4,3,2,1,9,8,7,6,5,4,3,2,1,9,8,7,6,5,4,3,2,1,10,9,8,7,6,5,4,3
%N A128118 At the n-th iteration the sequence of integers from n down to 1 are appended to the sequence a(n) times.
%H A128118 Reed Kelly, Feb 15 2007, <a href="/A128118/b128118.txt">Table of n, a(n) for n = 1..555</a>
%e A128118 a(4) = 2 so 4,3,2,1,4,3,2,1 is added to the end of the sequence at the fourth iteration.
%t A128118 crr[n_] := Module[ { A = {1,2,1,2,1}, i, j }, For [ i = 3, i <= n, i++, A = Join[ A, Flatten[ Table[ Range[i,1,-1], {A[[i]]} ]]]; ]; A ]
%Y A128118 Cf. A128117, A001462, A002260.
%K A128118 easy,nonn
%O A128118 1,2
%A A128118 _Reed Kelly_, Feb 15 2007