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 A013635 #20 Sep 08 2022 08:44:38
%S A013635 5,7,8,11,12,15,16,17,18,23,24,27,28,29,30,35,36,39,40,41,42,47,48,49,
%T A013635 50,51,52,59,60,63,64,65,66,67,68,75,76,77,78,83,84,87,88,89,90,95,96,
%U A013635 97,98,99,100,107,108,109,110,111,112,119,120,123,124,125,126
%N A013635 a(n) = prevprime(n) + n.
%H A013635 Vincenzo Librandi, <a href="/A013635/b013635.txt">Table of n, a(n) for n = 3..5000</a>
%p A013635 [ seq(prevprime(i)+i,i=3..100) ];
%t A013635 Table[n+NextPrime[n,-1],{n,3,60}] (* _Harvey P. Dale_, Mar 29 2019 *)
%o A013635 (Magma) [n + PreviousPrime(n): n in [3..70]]; // _Vincenzo Librandi_, Mar 30 2019
%o A013635 (PARI) a(n) = precprime(n-1) + n; \\ _Michel Marcus_, Mar 30 2019
%Y A013635 Cf. A007917, A049711.
%K A013635 nonn
%O A013635 3,1
%A A013635 _N. J. A. Sloane_