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 A037841 #12 Jan 21 2018 04:08:08
%S A037841 0,0,0,0,0,0,0,0,1,0,1,2,3,4,5,6,7,2,1,0,1,2,3,4,5,6,3,2,1,0,1,2,3,4,
%T A037841 5,4,3,2,1,0,1,2,3,4,5,4,3,2,1,0,1,2,3,6,5,4,3,2,1,0,1,2,7,6,5,4,3,2,
%U A037841 1,0,1,8,7,6,5,4,3,2,1,0,1,2,3,4,5,6,7,8,9,1
%N A037841 a(n)=Sum{|d(i)-d(i-1)|: i=1,...,m}, where Sum{d(i)*9^i: i=0,1,...,m} is the base 9 representation of n.
%C A037841 This is the base-9 total variation sequence; see A297330. - _Clark Kimberling_, Jan 18 2017
%H A037841 Clark Kimberling, <a href="/A037841/b037841.txt">Table of n, a(n) for n = 1..10000</a>
%t A037841 b = 9; z = 120; t = Table[Total@ Flatten@ Map[Abs@ Differences@ # &, Partition[IntegerDigits[n, b], 2, 1]], {n, z}] (* cf. Michael De Vlieger, A037834 *)
%Y A037841 Cf. A297330.
%K A037841 nonn,base
%O A037841 1,12
%A A037841 _Clark Kimberling_
%E A037841 Updated by _Clark Kimberling_, Jan 20 2018