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 A051308 #20 Aug 17 2015 03:30:49
%S A051308 5,2,11,3,331,19,199,53,21888927391,29833,101,71,23,311,7,72353,13,
%T A051308 227,96014559769,5641,41,82107739003,67,169637539,61,29,31319,17,97,
%U A051308 238591921,313,102065429,157,37,595553520313,244217,241,4773229353714971081083834237,103
%N A051308 Euclid-Mullin sequence (A000945) with initial value a(1)=5 instead of a(1)=2.
%C A051308 The initial primes 3 and 7 give essentially A000945.
%e A051308 5*2*11*3 + 1 = 331, which is prime; the least prime factor of 330*331 + 1 = 109231 = 19*5749 is 19, so a(6) = 19.
%t A051308 a[1]=5; a[n_] := First[ Flatten[ FactorInteger[ 1+Product[ a[ j ], {j, 1, n-1} ] ] ] ]; Array[a, 10]
%o A051308 (PARI) spf(n)=my(f=factor(n)[1,1]);f;
%o A051308 first(m)=my(v=vector(m));v[1]=5;for(i=2,m,v[i]=spf(1+prod(j=1,i-1,v[j])));v; \\ _Anders Hellström_, Aug 15 2015
%Y A051308 Cf. A000945, A000946, A005265, A005266.
%K A051308 nonn
%O A051308 1,1
%A A051308 _Labos Elemer_
%E A051308 a(38)-a(39) from _Robert Price_, Jul 19 2015