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 A088123 #17 Jul 25 2017 06:58:43
%S A088123 1,2,1,6,1,6,1,8,1,74,6,6,1,2,11,102,20,88,1,52,10,18,2,56,1,26,37,
%T A088123 216,1,78,1,28,21,160,3,276,30,1542,42,598,20,20,333,186,8,82,11,90,1,
%U A088123 246,1,240,83,58,9,76,1,16,21,700,60,10,87,250,62,406,2,502,140,186,1293,578
%N A088123 Let f(n,x) = 1 + 2x + 3x^2 + 5x^3 + 7x^4 + ... + prime(n)*x^n; a(n) = smallest value of x such that f(n,x) is a prime, or 0 if no such prime exists.
%H A088123 Vincenzo Librandi, <a href="/A088123/b088123.txt">Table of n, a(n) for n = 1..200</a>
%e A088123 a(4) = 6 as, A088122(4) = 10273 = f(4,6).
%t A088123 Table[Clear[x,n,eq];eq=Total[Table[Prime[n]x^n,{n,t}]]+1;x=1; While[ !PrimeQ[ eq],x++];x,{t,80}] (* _Harvey P. Dale_, Apr 27 2013 *)
%Y A088123 Cf. A088122.
%K A088123 nonn
%O A088123 1,2
%A A088123 _Amarnath Murthy_, Sep 25 2003
%E A088123 More terms from _Tom Mueller_, May 04 2004
%E A088123 More terms from _David Wasserman_, Jul 25 2005