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 A215697 #17 Aug 17 2014 16:38:36 %S A215697 3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,97,101, %T A215697 103,107,109,127,137,139,149,151,157,167,173,181,191,197,199,211,223, %U A215697 227,229,233,239,241,251,257,263,269,271,283,293,307,313,317,331 %N A215697 Primes p = 2x + 1 such that x^2 + x + 41 is prime. %H A215697 Pierre CAMI, <a href="/A215697/b215697.txt">Table of n, a(n) for n = 1..10000</a> %e A215697 17 is in the sequence because, given x = (17 - 1)/2 = 8, we have 8^2 + 8 + 41 = 113 which is prime. %t A215697 Select[Prime[Range[100]], PrimeQ[((# - 1)/2)^2 + ((# - 1)/2) + 41] &] (* _Alonso del Arte_, Aug 21 2012 *) %o A215697 (PARI) for(x=1, 1e3, if(ispseudoprime(2*x+1), if(ispseudoprime(x^2+x+41), print1(2*x+1, ", ")))) \\ _Felix Fröhlich_, Aug 16 2014 %Y A215697 Cf. A056561, A005846. %K A215697 nonn %O A215697 1,1 %A A215697 _Pierre CAMI_, Aug 21 2012