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 A117874 #10 Oct 31 2013 12:17:38
%S A117874 17,61,131,151,271,523,541,571,751,797,971,991,997,1291,1321,1361,
%T A117874 1741,1901,1913,2011,2179,2297,2341,2441,2447,2551,2791,2851,3301,
%U A117874 3511,3761,3803,4051,4391,4397,4423,4441,4561,4651,4703,4759,5101,5471,5483,5521
%N A117874 Primes for which the level is equal to 5 in A117563.
%H A117874 Remi Eismann, <a href="/A117874/b117874.txt">Table of n, a(n) for n=1..10000</a>
%e A117874 19=17+17 mod(3)=17+17 mod(15), level=5
%e A117874 157=151+151 mod(29)=151+151 mod(145) level=5
%e A117874 2203=2179+2179 mod(431)=2179+2179 mod(2155), level=5
%t A117874 f[n_] := Block[{d, j = 2, p = Prime@n}, d = Prime[n + 1] - p; While[j < p && Mod[p, j] != d, j++ ]; If[j == p, 0, j]]; g[n_] := Block[{d, k = p = Prime@n}, d = Prime[n + 1] - p; While[k > 0 && Mod[p, k] != d, k-- ]; If[k == 0, 0, k]]; h[n_] := Block[{a = f@n, b = g@n}, If[a == 0, 0, b/a]]; Prime@Select[ Range@763, h@# == 5 &] (* _Robert G. Wilson v_ *)
%Y A117874 Cf. A117078.
%K A117874 nonn
%O A117874 1,1
%A A117874 _Rémi Eismann_, May 02 2006
%E A117874 More terms from _Robert G. Wilson v_, May 06 2006
%E A117874 Edited by _N. J. A. Sloane_, May 14 2006