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 A073796 #7 Dec 09 2020 01:54:06
%S A073796 0,1,2,3,4,5,6,7,8,-9,-8,-7,-6,-5,-4,-3,-2,-1,-18,-17,-16,-15,-14,-13,
%T A073796 -12,-11,-10,-27,-26,-25,-24,-23,-22,-21,-20,-19,-36,-35,-34,-33,-32,
%U A073796 -31,-30,-29,-28,-45,-44,-43,-42,-41,-40,-39,-38,-37,-54,-53,-52,-51,-50,-49,-48,-47,-46
%N A073796 Replace 9^k with (-9)^k in base 9 expansion of n.
%C A073796 Base 9 representation for n (in lexicographic order) converted from base -9 to base 10.
%H A073796 Dana G. Korssjoen, Biyao Li, Stefan Steinerberger, Raghavendra Tripathi, and Ruimin Zhang, <a href="https://arxiv.org/abs/2012.04625">Finding structure in sequences of real numbers via graph theory: a problem list</a>, arXiv:2012.04625, Dec 08, 2020
%F A073796 a(9*k+m) = -9*a(k)+m for 0 <= m < 9. - _Chai Wah Wu_, Jan 16 2020
%t A073796 f[n_Integer, b_Integer] := Block[{l = IntegerDigits[n]}, Sum[l[[ -i]]*(-b)^(i - 1), {i, 1, Length[l]}]]; a = Table[ FromDigits[ IntegerDigits[n, 9]], {n, 0, 80}]; b = {}; Do[b = Append[b, f[a[[n]], 9]], {n, 1, 80}]; b
%Y A073796 Cf. A007095, A073790, A053985, A065369, A073791, A073792, A073793, A073794, A073795 & A073835.
%K A073796 base,easy,sign
%O A073796 0,3
%A A073796 _Robert G. Wilson v_, Aug 12 2002