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 A174615 #24 Apr 22 2025 10:48:59 %S A174615 0,0,0,0,0,0,0,0,0,0,2,41,262,1340,5359,19210,60150,172234,460553, %T A174615 1159167,2774702,6363475,14056367 %N A174615 Number of seven-prime Carmichael numbers less than 10^n. %D A174615 Paulo Ribenboim, The Little Book of Bigger Primes, Springer-Verlag NY 2004. See p. 220. %H A174615 Claude Goutier, <a href="http://www-labs.iro.umontreal.ca/~goutier/OEIS/A055553/">Text file readme.text summarizing enumeration of Carmichael numbers up to 10^22</a>. %H A174615 Claude Goutier, <a href="/A055553/a055553.txt">Text file readme.text summarizing enumeration of Carmichael numbers up to 10^22</a>. [Local copy, with permission] %H A174615 R. G. E. Pinch, <a href="http://s369624816.websitehome.co.uk/rgep/p82p.pdf">The Carmichael numbers up to 10^21</a>, Proceedings of Conference on Algorithmic Number Theory 2007. %e A174615 The smallest Carmichael number with 7 prime factors is 5394826801 = 7*13*17*23*31*67*73, and there is one other 10-digit example, so a(10)=2. %Y A174615 For k-prime Carmichael numbers up to 10^n for k = 3,4,...,11, see A132195, A174612, A174613, A174614, A174615, A174616, A174617, A299710, A299711. %Y A174615 Cf. A002997, A006931, A055553. %K A174615 nonn,more %O A174615 0,11 %A A174615 _Michel Lagneau_, Mar 23 2010 %E A174615 a(22) from _Claude Goutier_ added by _Amiram Eldar_, Apr 19 2024