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 A231594 #12 Jun 16 2019 13:59:25
%S A231594 1,3,33,360,3816,38911,396016,4015732,40543671,408462140,4109293287,
%T A231594 41296082801,414669334188,4161237526152
%N A231594 Total number of 5's digits in primes less than 10^n.
%e A231594 a(2)=3, since there are 3 5's in primes less than 100. Namely: 5, 53, 59.
%t A231594 Table[Count[IntegerDigits[Prime[Range[PrimePi[10^n - 1]]]], 5, 2], {n, 7}] (* _Robert Price_, Jun 16 2019 *)
%Y A231594 Cf. A231411, A231590-A231598, A119290, A119291-A119300.
%K A231594 more,nonn,base
%O A231594 1,2
%A A231594 _Robert Price_, Nov 11 2013
%E A231594 a(14) from _Giovanni Resta_, Jul 20 2015