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 A192169 #6 Oct 21 2019 15:02:02
%S A192169 0,3,7,15,55,63,175,247,255,295,943,1015,1023,3367,4015,4087,4095,
%T A192169 6487,9823,15655,16303,16375,16383,58975,64807,65455,65527,65535,
%U A192169 203095,255583,261415,262063,262135,262143,517135,989527,1042015,1047847,1048495,1048567
%N A192169 Monotonic ordering of nonnegative differences 4^i-9^j, for 40>= i>=0, j>=0.
%t A192169 c = 4; d = 9; t[i_, j_] := c^i - d^j;
%t A192169 u = Table[t[i, j], {i, 0, 40}, {j, 0, i*Log[d, c]}];
%t A192169 v = Union[Flatten[u ]]
%Y A192169 Cf. A192170.
%K A192169 nonn
%O A192169 1,2
%A A192169 _Clark Kimberling_, Jun 24 2011