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 A124001 #35 Mar 11 2023 08:39:44
%S A124001 2,1,1,19,7,151,37,139,37,7,277,817,61,1267,97,2371,1549,19,619,97,
%T A124001 391,409,649,5527,2731,559,949,427,601,2797,1681,7189,2449,6751,7597,
%U A124001 8419,16879,871,5569,10327,16111,2131,6121,23329,5179,4249,2641,2257,3997
%N A124001 Difference between first twin prime > 10^n and 10^n.
%C A124001 a(n) >= A033873(n) and a(n) = A033873(n) for n = 1, 2, 4, 9.
%C A124001 As N increases, the ratio (Sum_{n=1..N} a(n)/n^2)/N tends to 4. - _Pierre CAMI_, Jul 12 2013
%H A124001 Robert G. Wilson v, <a href="/A124001/b124001.txt">Table of n, a(n) for n = 0..1250</a> (first 476 terms from _Pierre CAMI_).
%F A124001 a(n) = A092245(n+1) - 10^n. - _Robert G. Wilson v_, Nov 28 2015
%e A124001 a(0) = 2 because 3 and 5 are twin primes and 3 - 10^0 = 2,
%e A124001 a(1) = 1 because 11 and 13 are twin primes and 11 - 10^1 = 1,
%e A124001 a(2) = 1 because 101 and 103 are twin primes and 101 - 10^2 = 1,
%e A124001 a(3) = 19 because 1019 and 1021 are twin primes and 1019 - 10^3 = 19, etc.
%t A124001 f[n_] := Block[{p = q = NextPrime[10^n]}, While[p + 2 != q, p = q; q = NextPrime@ q]; p - 10^n]; Array[f, 49, 0] (* _Robert G. Wilson v_, Nov 28 2015 *)
%t A124001 ftp[n_]:=Module[{p=NextPrime[n]},While[CompositeQ[p+2],p=NextPrime[p]];p-n]; Table[ftp[10^n],{n,0,50}] (* _Harvey P. Dale_, Oct 15 2019 *)
%Y A124001 Cf. A033873, A092245.
%K A124001 nonn
%O A124001 0,1
%A A124001 _Zak Seidov_, Nov 01 2006