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 A192161 #7 Oct 21 2019 14:52:53 %S A192161 0,3,11,15,39,59,63,131,231,251,255,399,759,899,971,999,1019,1023, %T A192161 3471,3971,4071,4091,4095,13259,15759,16259,16359,16379,16383,49911, %U A192161 62411,64911,65411,65511,65531,65535,184019,246519,259019,261519,262019,262119,262139 %N A192161 Monotonic ordering of nonnegative differences 4^i-5^j, for 40>= i>=0, j>=0. %e A192161 The differences accrue like this: %e A192161 1-1 %e A192161 4-1 %e A192161 16-5......16-1 %e A192161 64-25.....64-5.....64-1 %e A192161 256-125...256-25...256-5...256-1 %t A192161 c = 4; d = 5; t[i_, j_] := c^i - d^j; %t A192161 u = Table[t[i, j], {i, 0, 40}, {j, 0, i*Log[d, c]}]; %t A192161 v = Union[Flatten[u ]] %Y A192161 Cf. A192162. %K A192161 nonn %O A192161 1,2 %A A192161 _Clark Kimberling_, Jun 24 2011