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 A228113 #23 Feb 16 2025 08:33:20 %S A228113 5,21,142,1059,8360,68940,586140,5096885,45085903,404203228, %T A228113 3663001812,33489858047,308457620524,2858876200536,26639628764285, %U A228113 249393770865090,2344318815695001,22116397127183516,209317713015989446,1986761935255798075,18906449883376272709 %N A228113 First differences of A057793. %C A228113 This sequence is an approximation to the number of primes with n digits (A006879). The error in the approximation is tabulated in A228114. %C A228113 Because A057793(n) = Riemann(10^n) is not defined for n=0, we set its value to zero for our purpose of defining the differences. %D A228113 John H. Conway and R. K. Guy, "The Book of Numbers," Copernicus, an imprint of Springer-Verlag, NY, 1996, page 144-146. %H A228113 Vladimir Pletser, <a href="/A228113/b228113.txt">Table of n, a(n) for n = 1..100</a> [a(40)-a(41) corrected by Sean A. Irvine] %H A228113 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PrimeCountingFunction.html">Prime Counting Function</a>. %H A228113 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RiemannPrimeCountingFunction.html">Riemann Prime Counting Function</a>. %F A228113 a(n) = A057793(n) - A057793(n-1). %e A228113 For n=1, A057793(1) - A057793(0) = 5 - 0 = 5. %Y A228113 Cf. A006879, A057793, A228111, A228112, A228114, A228115, A228116. %K A228113 nonn %O A228113 1,1 %A A228113 _Vladimir Pletser_, Aug 10 2013