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 A387500 #9 Sep 02 2025 16:03:35
%S A387500 5,36,420,4644,51060,518238,5206320,52565169,528113445,5302625562
%N A387500 Median of twin prime pairs with n decimal digits.
%C A387500 It is assumed that a pair of twin primes is characterized by its mean. The median of an even number of values is taken as the arithmetic mean of the two central elements in their sorted list.
%e A387500 a(1): 2 pairs {3,5}, {5,7}, median = mean of {4,6} = 5;
%e A387500 a(2): 6 pairs {11,13}, {17,19}, {29,31}, {41,43}, {59,61}, {71,73}, median = mean of {30,42} = 36.
%t A387500 a[n_]:=Module[{s={},p=NextPrime[10^(n-1)]},While[p<10^n-4,If[PrimeQ[p+2],AppendTo[s,p+1]];p=NextPrime[p]];Median[s]];Array[a,7] (* _James C. McMahon_, Sep 02 2025 *)
%Y A387500 Cf. A001097, A007508, A309329.
%K A387500 nonn,base,more,new
%O A387500 1,1
%A A387500 _Hugo Pfoertner_, Sep 02 2025