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 A386007 #10 Jul 21 2025 22:00:10
%S A386007 2,3,70,2626355
%N A386007 Least k such that there are exactly n primes that are popular on the interval [2,k] (see A385503); i.e., exactly n primes share the lead as the most common greatest prime factor of the numbers 2..k.
%e A386007 a(3) = 70, because the 3 primes 3, 5, and 7 all occur A385652(70) = 10 times (the maximum) as the greatest prime factor of the numbers 2..70, and for earlier intervals there is never a tie between 3 numbers.
%e A386007 a(4) = 2626355, because the 4 primes 73, 83, 109, and 113 all occur A385652(2626355) = 7634 times (the maximum) as the greatest prime factor of the numbers 2..2626355, and for earlier intervals there is never a tie between 4 numbers.
%t A386007 gpf[n_]:=FactorInteger[n][[-1,1]];a[n_]:=Module[{k=1},Until[Length[Commonest[gpf/@Range[2,k]]]==n,k++];k] (* _James C. McMahon_, Jul 20 2025 *)
%Y A386007 Cf. A006530, A385503, A385652.
%K A386007 nonn,hard,more
%O A386007 1,1
%A A386007 _Pontus von Brömssen_, Jul 14 2025