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 A105121 #17 Apr 19 2016 01:07:35
%S A105121 0,1,1,1,1,3,3,3,3,3,9,15,47,63,67,69,93,99,105,111,111,115,121,139,
%T A105121 165,189,205,231,249,253,285,291,309,323,363,367,369,377,395,401,465,
%U A105121 501,533,587,591,609,629,657,693,729,735,783,787,825,863,863,869,917,981
%N A105121 Numbers k(n) from A105120.
%H A105121 Zak Seidov, <a href="/A105121/b105121.txt">Table of n, a(n) for n = 1..200.</a>
%t A105121 a[1] = {2, 0}; a[n_] := a[n] = Block[{m = 2a[n - 1][[1]], k = a[n - 1][[2]]}, While[ !PrimeQ[m + k], k++ ]; {m + k, k}]; Table[ a[n][[2]], {n, 59}] (* _Robert G. Wilson v_, Apr 08 2005 *)
%o A105121 (PARI) a=2;print1(k=0,",");for(n=2,59,j=k;while(!isprime(2*a+j),j++);print1(k=j,",");a=2*a+k) \\ _Klaus Brockhaus_
%Y A105121 Cf. A105120.
%K A105121 nonn
%O A105121 1,6
%A A105121 _Yasutoshi Kohmoto_, Apr 08 2005
%E A105121 Edited, corrected and extended by _Klaus Brockhaus_ and _Robert G. Wilson v_, Apr 08 2005