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 A039506 #23 Apr 02 2025 19:00:18 %S A039506 3,23,99,420,1807,8287,40017,202208,1059807,5736717,31911465, %T A039506 182019293,1060723057 %N A039506 Number of cluster primes less than 10^n. %C A039506 The Blecksmith paper gives incorrect values of a(n) for n>8. - _T. D. Noe_, Jul 21 2006 %H A039506 Richard Blecksmith, Paul Erdős and J. L. Selfridge, <a href="http://www.jstor.org/stable/2589585">Cluster Primes</a>, Amer. Math. Monthly, 106 (1999), 43-48. %H A039506 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ClusterPrime.html">Cluster Prime.</a> %H A039506 Wikipedia, <a href="https://en.wikipedia.org/wiki/Cluster_prime">Cluster prime</a>. %H A039506 <a href="/index/Pri#primepop">Index entries for sequences related to numbers of primes in various ranges</a> %Y A039506 Cf. A038133, A038134, A039507. %Y A039506 Cf. A121044, A121045 (cluster primes near 10^n). %K A039506 nonn,more %O A039506 1,1 %A A039506 _Christian G. Bower_, Feb 15 1999 %E A039506 Corrected by _T. D. Noe_, Jul 21 2006