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 A087719 #20 Aug 24 2024 22:44:17
%S A087719 15,27,57,135,345,927,2577,7335,21225,62127,183297,543735,1618905,
%T A087719 4832127,14447217,43243335,129533385,388206927,1163834337,3489930135,
%U A087719 10466644665,31393642527,94168344657,282479868135
%N A087719 Least number m such that the number of numbers k <= m with k > spf(k)^n exceeds the number of numbers with k <= spf(k)^n.
%C A087719 m<a(n): #{k: k>spf(k)^n & 1<=k<=m} <= m/2;
%C A087719 m>=a(n): #{k: k>spf(k)^n & 1<=k<=m} > m/2.
%F A087719 Numbers so far satisfy a(n) = 3^n + 3*2^n + 6. - _Ralf Stephan_, May 10 2004
%F A087719 Empirical G.f.: 3*x*(5-21*x+20*x^2)/(1-x)/(1-2*x)/(1-3*x). - _Colin Barker_, Feb 22 2012
%Y A087719 Cf. A088382, A088382, A088380, A088381, A000430, A080257.
%K A087719 nonn
%O A087719 1,1
%A A087719 _Reinhard Zumkeller_, Sep 29 2003
%E A087719 a(14)-a(24) from _Giovanni Resta_, May 23 2013