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 A112600 #7 Apr 19 2016 01:16:08 %S A112600 2,5,11,37,13,23,19,23,37,127,47,61,61,47,67,61,277,83,79,97,127,83, %T A112600 101,131,269,109,131,109,113,157,137,181,157,181,151,173,173,179,173, %U A112600 211,223,251,193,197,223,233,223,251,271,241,239,269,293,281,313,347,293 %N A112600 Smallest prime factor of A111392(n). %C A112600 For all i, if i<n+2 then GCD(p_i,A111392(n))=1, where p_i is i-th prime. %C A112600 A111392: a(n) = Product_{i=1..n-1} (Product_{k=1..i} p_k + Product_{k=i+1..n} p_k). - _Robert G. Wilson v_, Dec 22 2005 %t A112600 f[n_] := Product[(Product[Prime[k], {k, i}] + Product[Prime[k], {k, i + 1, n}]), {i, n - 1}]; f[1] = 2; g[n_] := Block[{k = 1}, While[Mod[f[n], Prime[k]] != 0, k++ ]; Prime@k]; Array[g, 20] (* _Robert G. Wilson v_ *) %Y A112600 Cf. A111392. %K A112600 nonn %O A112600 1,1 %A A112600 _Yasutoshi Kohmoto_, Dec 15 2005 %E A112600 More terms from _Robert G. Wilson v_, Dec 22 2005