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 A083275 #14 Jun 23 2015 11:12:18
%S A083275 3,1,2,4,7,5,6,11,12,10,13,17,14,16,15,8,18,23,21,26,22,27,41,30,20,
%T A083275 57,32,29,24,65,42,38,28,63,35,19,58,31,36,61,45,37,33,69,53,67,127,
%U A083275 40,95,25,86,48,39,72,70,79,54,74,91,125,85,94,46,9,80,60,119,167,139,90,49
%N A083275 a(n) = smallest number not occurring earlier such that a(1)*a(2)*...*a(n) - 1 is prime.
%H A083275 Alois P. Heinz and Giovanni Resta, <a href="/A083275/b083275.txt">Table of n, a(n) for n = 1..1200</a> (first 300 terms from Alois P. Heinz)
%p A083275 b:= proc() false end:
%p A083275 m:= proc(n) option remember; a(n)*m(n-1) end: m(0):=1:
%p A083275 a:= proc(n) option remember; local k; for k while b(k)
%p A083275 or not isprime(k*m(n-1)-1) do od; b(k):=true; k
%p A083275 end:
%p A083275 seq(a(n), n=1..80); # _Alois P. Heinz_, Jun 17 2015
%t A083275 p=1; L={}; Do[k=1; While[ MemberQ[L, k] || !PrimeQ[p*k - 1], k++]; p *= k; AppendTo[L, k], {30}]; L (* _Giovanni Resta_, Jun 23 2015 *)
%o A083275 (PARI) v=[3];n=1;while(n<100,s=-1+n*prod(i=1,#v,v[i]);if(isprime(s)&&!vecsearch(vecsort(v),n),v=concat(v,n);n=0);n++);v \\ _Derek Orr_, Jun 16 2015
%Y A083275 Cf. A051957, A036013, A073673, A259262.
%K A083275 nonn
%O A083275 1,1
%A A083275 _Vladeta Jovovic_, Jun 01 2003
%E A083275 Name corrected by _Derek Orr_, Jun 16 2015