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 A307331 #11 Apr 04 2019 18:25:13 %S A307331 6,26,125,827,7584,74083,740368,7399353,73976842,739778038,7397814233, %T A307331 73979274540 %N A307331 The number of Ulam numbers below 10^n. %C A307331 The terms a(1)-a(12) are from the paper by Gibbs and McCranie. %C A307331 The number of Ulam numbers not exceeding 10^n can be calculated from this sequence using the fact that up to 10^12 the only powers of 10 that are Ulam numbers are 10^6 and 10^11. %C A307331 The asymptotic density D of Ulam numbers is known to be 0 <= D <= 0.4. Gibbs and McCranie estimated it from this sequence as ~ 0.073979. %H A307331 Philip Gibbs, Judson McCranie, <a href="https://www.researchgate.net/publication/320980165_The_Ulam_Numbers_up_to_One_Trillion">The Ulam Numbers up to One Trillion</a>, (2017). %Y A307331 Cf. A002858. %K A307331 nonn,more %O A307331 1,1 %A A307331 _Amiram Eldar_, Apr 02 2019