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 A037840 #12 Jan 21 2018 04:08:01
%S A037840 0,0,0,0,0,0,0,1,0,1,2,3,4,5,6,2,1,0,1,2,3,4,5,3,2,1,0,1,2,3,4,4,3,2,
%T A037840 1,0,1,2,3,5,4,3,2,1,0,1,2,6,5,4,3,2,1,0,1,7,6,5,4,3,2,1,0,1,2,3,4,5,
%U A037840 6,7,8,1,0,1,2,3,4,5,6,3,2,1,2,3,4,5,6,5,4,3
%N A037840 a(n)=Sum{|d(i)-d(i-1)|: i=1,...,m}, where Sum{d(i)*8^i: i=0,1,...,m} is the base 8 representation of n.
%C A037840 This is the base-8 total variation sequence; see A297330. - _Clark Kimberling_, Jan 18 2017
%H A037840 Clark Kimberling, <a href="/A037840/b037840.txt">Table of n, a(n) for n = 1..10000</a>
%t A037840 b = 8; z = 120; t = Table[Total@ Flatten@ Map[Abs@ Differences@ # &, Partition[IntegerDigits[n, b], 2, 1]], {n, z}] (* cf. Michael De Vlieger, A037834 *)
%Y A037840 Cf. A297330.
%K A037840 nonn,base
%O A037840 1,11
%A A037840 _Clark Kimberling_
%E A037840 Updated by _Clark Kimberling_, Jan 20 2018