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 A055255 #11 Oct 27 2023 22:00:46 %S A055255 0,0,0,1,1,2,1,2,2,2,2,1,2,2,4,4,5,4,6,6,7,6,4,5,8,9,8,6,8,8,8,6,9,6, %T A055255 8,6,7,8,7,8,10,9,7,9,11,11,10,11,12,10,10,8,16,13,12,11,9,16,18,14, %U A055255 14,17,19,16,19,13,17,14,14,14,14,14,17,16,15,16,16,15,25,23,22 %N A055255 Number of even digits in 3^n. %H A055255 Seiichi Manyama, <a href="/A055255/b055255.txt">Table of n, a(n) for n = 0..10000</a> %o A055255 (PARI) a(n) = #select(x->((x%2) == 0), digits(3^n)); \\ _Michel Marcus_, Nov 22 2019 %Y A055255 Cf. A055256, A034888. %K A055255 nonn,base,easy %O A055255 0,6 %A A055255 _Asher Auel_, May 05 2000