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 A031960 #17 Aug 10 2021 17:11:10 %S A031960 66,67,68,69,70,71,80,83,84,85,86,87,88,90,92,93,94,95,96,98,99,101, %T A031960 102,103,104,106,107,108,110,111,112,114,115,116,117,119,120,122,123, %U A031960 124,125,126,129,131,132,133,134,135,136,139,140 %N A031960 Numbers with exactly three distinct base-8 digits. %H A031960 <a href="/index/Ar#2-automatic">Index entries for 2-automatic sequences</a>. %t A031960 dd8Q[n_]:=Length[Union[IntegerDigits[n,8]]]==3; Select[Range[200],dd8Q] (* _Harvey P. Dale_, Nov 10 2013 *) %o A031960 (PARI) is(n)=#Set(digits(n,8))==3 \\ _Charles R Greathouse IV_, Feb 15 2017 %Y A031960 Cf. A007094. %K A031960 nonn,base,easy %O A031960 1,1 %A A031960 _Clark Kimberling_