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 A162237 #11 Oct 07 2024 01:17:42 %S A162237 11,13,17,31,41,61,71,73,79,83,89,97,101,103,107,109,127,131,149,151, %T A162237 167,181,191,193,197,199,211,223,227,233,241,251,269,271,277,281,283, %U A162237 307,311,317,331,337,347,367,383,389,397,401,409,421,431,433,439,443 %N A162237 Primes p such that p^2+3*p+1 is not prime. %H A162237 Vincenzo Librandi, <a href="/A162237/b162237.txt">Table of n, a(n) for n = 1..1000</a> %e A162237 p=11, p^2+3*p+1=155=5*31; p=13, p^2+3*p+1=209=11*19; p=17, p^2+3*p+1=341=11*31. %t A162237 Select[Range[0, 500], PrimeQ[#] && !PrimeQ[#^2 + 3 # + 1] &] (* _Vincenzo Librandi_, Sep 11 2013 *) %o A162237 (Magma) [p: p in PrimesUpTo(500) | not IsPrime(p^2+3*p+1)]; // _Vincenzo Librandi_, Sep 11 2013 %Y A162237 Cf. A153590. %K A162237 nonn,easy %O A162237 1,1 %A A162237 _Vincenzo Librandi_, Jun 28 2009