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 A098566 #10 Mar 28 2015 22:14:25
%S A098566 3,5,7,7,13,17,19,29,53,157,79,101,613,641,2633,2161,1697,2293,12251,
%T A098566 4283,7573,7243,9433,22381,29411,16333
%N A098566 Smallest prime P such that P# - Mersenne-prime(n) is prime.
%t A098566 mexp = {the list in A000043}; Primorial[n_] := Product[ Prime[i], {i, n}]; f[n_] := Block[{k = 1}, While[Primorial[k] < 2^mexp[[n]] || !PrimeQ[ Primorial[k] - 2^mexp[[n]] + 1], k++ ]; Prime[k]]; Table[ f[n], {n, 15}] (* _Robert G. Wilson v_, Sep 28 2004 *)
%Y A098566 Cf. A098567.
%K A098566 more,nonn
%O A098566 1,1
%A A098566 _Pierre CAMI_, Sep 15 2004
%E A098566 Corrected by _Robert G. Wilson v_, Sep 28 2004
%E A098566 a(19)-a(26) from _Donovan Johnson_, Feb 22 2008