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 A055144 #6 Oct 27 2019 00:12:09 %S A055144 1,5,16,48,145,436,1309,3929,11789,35367,106103,318310,954932,2864798, %T A055144 8594395,25783185,77349555,232048666,696145998,2088437995,6265313986, %U A055144 18795941958,56387825876,169163477629,507490432888,1522471298664 %N A055144 The first n digits of the juxtaposition of the base-3 numbers converted to decimal. %e A055144 1 (1); 12 (5); 121 (16); 1210 (48); 12101 (145); 121011 (436); ... %Y A055144 Cf. A054635, A054637, A055072, A055073, A055143-A055150. %K A055144 nonn,base %O A055144 1,2 %A A055144 _Patrick De Geest_, Apr 15 2000