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 A192160 #6 Oct 21 2019 14:52:34
%S A192160 0,1,7,9,19,73,91,97,99,271,757,919,973,991,997,999,3439,7813,9271,
%T A192160 9757,9919,9973,9991,9997,9999,40951,80317,93439,97813,99271,99757,
%U A192160 99919,99973,99991,99997,99999,468559,822853,940951,980317,993439,997813,999271
%N A192160 Monotonic ordering of nonnegative differences 10^i-3^j, for 40>=i>=0, j>=0.
%t A192160 c = 10; d = 3; t[i_, j_] := c^i - d^j;
%t A192160 u = Table[t[i, j], {i, 0, 40}, {j, 0, i*Log[d, c]}];
%t A192160 v = Union[Flatten[u ]]
%Y A192160 Cf. A192159.
%K A192160 nonn
%O A192160 1,3
%A A192160 _Clark Kimberling_, Jun 24 2011