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 A216568 #22 Sep 19 2012 12:19:33
%S A216568 2,1,4,2,4,8,4,2,6,6,2,2,4,6,6,4,6,8,6,4,14,2,4,16,2,10,6,6,6,6,6,4,4,
%T A216568 2,10,12,2,6,10,4,10,8,22,8,4,2,2,8,4,2,16,6,14,12,12,4,6,2,12,4,6,4,
%U A216568 2,10,6,6,2,2,6,8,10,6,2,6,2,4,6,6,22
%N A216568 Smallest k such that prime(n)*k-1 is prime.
%H A216568 T. D. Noe, <a href="/A216568/b216568.txt">Table of n, a(n) for n = 1..10000</a>
%t A216568 Table[k = 1; While[! PrimeQ[Prime[n]*k - 1], k++]; k, {n, 100}] (* _T. D. Noe_, Sep 19 2012 *)
%Y A216568 Cf. A035096, A034693, A053989.
%K A216568 nonn
%O A216568 1,1
%A A216568 _Alex Ratushnyak_, Sep 19 2012