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 A217131 #8 Jan 24 2014 01:17:46 %S A217131 2,4,8,10,50,106,182,293,964,1108,1654,1756,4601,8870,15100,17446, %T A217131 22742,34570,50150,95276 %N A217131 Numbers n such that 7^n - 8 is prime. %C A217131 a(21) > 10^5. - _Robert Price_, Jan 23 2014 %t A217131 Select[Range[1, 5000], PrimeQ[7^# - 8] &] %o A217131 (PARI) for(n=1, 5*10^3, if(isprime(7^n-8), print1(n, ", "))) %Y A217131 Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213. %K A217131 nonn %O A217131 1,1 %A A217131 _Vincenzo Librandi_, Oct 01 2012 %E A217131 a(14)-a(20) from _Robert Price_, Jan 23 2014