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 A370920 #7 Mar 17 2024 23:37:36
%S A370920 6,15,18,19,33,42,45,46,54,55,57,58,60,87,96,99,100,114,123,126,127,
%T A370920 135,136,138,139,141,162,163,165,166,168,171,172,174,175,177,180,181,
%U A370920 249,258,261,262,276,285,288,289,297,298,300,301,303,330,339,342,343
%N A370920 Positive integers in whose ternary representation 2 occurs at least once, and every 2 is followed by 0.
%F A370920 The ternary representations of 6, 15, and 18 are 20, 120, and 200.
%t A370920 Map[#[[1]] &, Select[Map[{#, #[[1]] > 0 && #[[1]] == #[[2]] &[{Length[
%t A370920 StringCases[#, "2"]], Length[StringCases[#, "20"]]}] &[
%t A370920 IntegerString[#, 3]]} &, Range[500]], #[[2]] &]] (* _Peter J. C. Moses_, Mar 05 2024 *)
%Y A370920 Cf. A007089, A074940.
%Y A370920 Cf. A370916, A370917, A370918, A370919, A370921, A370922, A370923.
%K A370920 nonn,base
%O A370920 1,1
%A A370920 _Clark Kimberling_, Mar 16 2024