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 A192165 #6 Oct 21 2019 14:59:26
%S A192165 0,3,9,15,57,63,207,249,255,681,975,1017,1023,1695,3753,4047,4089,
%T A192165 4095,13983,16041,16335,16377,16383,48729,63135,65193,65487,65529,
%U A192165 65535,144495,225033,245337,259743,261801,262095,262137,262143,930927,1031769,1046175
%N A192165 Monotonic ordering of nonnegative differences 4^i-7^j, for 40>= i>=0, j>=0.
%t A192165 c = 4; d = 7; t[i_, j_] := c^i - d^j;
%t A192165 u = Table[t[i, j], {i, 0, 40}, {j, 0, i*Log[d, c]}];
%t A192165 v = Union[Flatten[u ]]
%Y A192165 Cf. A192166.
%K A192165 nonn
%O A192165 1,2
%A A192165 _Clark Kimberling_, Jun 24 2011