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 A161719 #31 Jun 17 2013 13:28:48 %S A161719 4,4,10,40,990,8712,1691820,69466840,6173190532,4139897208540 %N A161719 Least number k such that 7^(2^i) + k is prime for i = 0,1,..,n-1. %e A161719 a(5) = 990 because k = 990 is the minimal k such that N = 7^(2^i) + k is prime for i = 0, 1, 2, 3, 4; N = 997, 1039, 3391, 5765791, 33232930570591. But 7^(2^5) + 990 is divisible by 37 and four other primes. %Y A161719 Cf. A129613, A225560 A226281, A226707. %K A161719 nonn,more %O A161719 1,1 %A A161719 _Robin Garcia_, Jun 16 2013 %E A161719 a(10) from _Giovanni Resta_, Jun 16 2013