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 A055730 #43 Jun 13 2025 08:19:57
%S A055730 0,3,9,30,114,445,1821,7671,33118,145713,650133,2934858,13375865,
%T A055730 61444585,284140656,1321453490,6175961983,28988040005,136575061279,
%U A055730 645620925545,3061129684411,14552990145243,69354801708586,331251325552977,1585299642009257,7600886353341754,36504944044424979
%N A055730 Number of primes <= 5^n.
%H A055730 Robert Price, <a href="/A055730/b055730.txt">Table of n, a(n) for n = 0..34</a>
%H A055730 <a href="/index/Pri#primepop">Index entries for sequences related to numbers of primes in various ranges</a>
%F A055730 a(n) = A000720(A000351(n)). - _Michel Marcus_, Aug 25 2014
%t A055730 Table[PrimePi[5^n], {n, 0, 19}]
%o A055730 (PARI) a(n) = primepi(5^n); \\ _Michel Marcus_, Aug 25 2014
%Y A055730 Cf. A006880, A007053 and A040014.
%K A055730 nonn
%O A055730 0,2
%A A055730 _Robert G. Wilson v_, Jun 09 2000
%E A055730 a(19) corrected by _Henri Lifchitz_, Nov 11 2012
%E A055730 a(20)-a(27) from _Henri Lifchitz_, Nov 11 2012
%E A055730 a(28)-a(32) from _Henri Lifchitz_, Aug 25 2014
%E A055730 Definition corrected by _Jean-Claude Arbaut_, Oct 07 2015
%E A055730 a(33) from _Robert Price_, May 07 2025