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 A014891 #12 Sep 04 2024 19:11:14
%S A014891 3878,3879,3880,3881,3882,3883,3888,46656,50534,50535,50536,50537,
%T A014891 50538,50539,50544
%N A014891 n is equal to the number of 2's in all numbers <= n written in base 6.
%t A014891 Module[{nn=51000,d2},d2=Accumulate[DigitCount[#,6,2]&/@Range[nn]];Select[ Thread[ {Range[ nn],d2}],#[[1]]==#[[2]]&]][[;;,1]] (* _Harvey P. Dale_, Sep 04 2024 *)
%Y A014891 Cf. A014778.
%K A014891 nonn,base,fini,full
%O A014891 1,1
%A A014891 _Olivier Gérard_
%E A014891 List proved complete by _Hugo van der Sanden_ (cf. A014886).