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 A049716 #15 Jul 06 2018 17:11:05
%S A049716 1,2,2,2,4,2,2,4,2,2,4,2,4,6,2,2,4,6,2,4,2,2,4,2,4,6,2,4,6,2,2,4,6,2,
%T A049716 4,2,2,4,6,2,4,2,4,6,2,4,6,8,2,4,2,2,4,2,2,4,2,4,6,8,10,12,14,2,4,2,4,
%U A049716 6,2,2,4,6,8,10,2,2,4,6,2,4,6,2,4,2,4,6,2,4,6,2,2,4
%N A049716 a(n) = 2*n + 1 - prevprime(2*n + 1).
%H A049716 Robert Israel, <a href="/A049716/b049716.txt">Table of n, a(n) for n = 1..10000</a>
%F A049716 a(n) = A049711(2*n+1). - _R. J. Mathar_, Oct 26 2015
%e A049716 n: 1 2 3 4 5 6 7 8 ...
%e A049716 2n+1: 3 5 7 9 11 13 15 17 ...
%e A049716 pp: 2 3 5 7 7 11 13 13 ...
%e A049716 diff: 1 2 2 2 4 2 2 4 ...
%p A049716 seq(2*n+1-prevprime(2*n+1), n=1..100); # _Robert Israel_, Jul 05 2018
%t A049716 Table[2n+1-NextPrime[2n+1,-1],{n,100}] (* _Harvey P. Dale_, Sep 21 2013 *)
%o A049716 (PARI) a(n) = 2*n+1-precprime(2*n); \\ _Michel Marcus_, Jul 06 2018
%Y A049716 Cf. A049613, A049653, A049711, A049847.
%K A049716 nonn
%O A049716 1,2
%A A049716 _N. J. A. Sloane_