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 A096499 #6 Sep 06 2015 13:02:49
%S A096499 6,4,8,20,10,60,16,4,24,54,46,46,70,176,84,12,40,134,104,104,92,24,84,
%T A096499 270,300,130,414,90,88,240,148,198,12,64,12,300,66,70,80,102,420,142,
%U A096499 630,140,600,88,176,312,80,96,460,132,420,284,144,408,312,180,44,300
%N A096499 Difference between prime following and prime preceding n-th repunit.
%F A096499 a(n) = A096497(n) - A096498(n) = A096869(n) + A096870(n).
%e A096499 n=2: 2nd repunit=11, 13-7=6=a[2].
%t A096499 <<NumberTheory`NumberTheoryFunctions` Table[NextPrime[(10^n-1)/9]-PreviousPrime[(10^n-1)/9], {n, 2, 100}]
%t A096499 dpf[n_]:=Module[{ru=FromDigits[PadRight[{},n,1]]},NextPrime[ru]-NextPrime[ ru,-1]]; Array[dpf,60,2] (* _Harvey P. Dale_, Sep 06 2015 *)
%Y A096499 Cf. A068693, A002275, A096497, A096498.
%K A096499 nonn
%O A096499 2,1
%A A096499 _Labos Elemer_, Jul 09 2004