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 A038819 #20 Apr 03 2023 10:36:09
%S A038819 455052511,882206716,1300005926,1711955433,2119654578,2524038155,
%T A038819 2925699539,3325059246,3722428991,4118054813,4512105232,4904759399,
%U A038819 5296138250,5686326158,6075437956,6463533937,6850690633,7236978160
%N A038819 Number of primes less than n*10^10.
%H A038819 Robert G. Wilson v, <a href="/A038819/b038819.txt">Table of n, a(n) for n = 1..10000</a>
%H A038819 Tomás Oliveira e Silva, <a href="http://sweet.ua.pt/tos/primes.html">Tables of values of pi(x) and of pi2(x)</a>
%H A038819 Andrew R. Booker, <a href="https://t5k.org/nthprime/">The Nth Prime Page</a>
%t A038819 Table[ PrimePi[ n*10^10 ], {n, 1, 18}]
%o A038819 (PARI) a(n)=primepi(10^10*n) \\ _Charles R Greathouse IV_, Apr 29 2015
%Y A038819 Cf. A038801, A028505, A038812, A038813, A038814, A038815, A038816, A038817, A038818, A038820, A038821, A080122, A080123, A080124, A080125, A080126, A080127, A080128, A080129.
%K A038819 nonn
%O A038819 1,1
%A A038819 _Jeff Burch_
%E A038819 Edited and extended by _Robert G. Wilson v_, Jan 29 2003