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 A141489 #17 Jul 28 2025 00:01:52 %S A141489 0,2,3,4,7,9,10,11,13,14,17,18,20,21,23,24,25,27,28,30,31,34,37,41,42, %T A141489 44,48,49,51,53,56,59,60,63,65,66,67,69,70,73,74,77,79,80,81,83,88,90, %U A141489 91,93,94,95,100,101,104,107,111,114,115,116,119,122,125,129,135,137 %N A141489 Numbers k such that k^2 + k + 257 is prime. %H A141489 Harvey P. Dale, <a href="/A141489/b141489.txt">Table of n, a(n) for n = 1..1000</a> %e A141489 If k=0, then k^2 + k + 257 = 257 (prime). %e A141489 If k=100, then k^2 + k + 257 = 10357 (prime). %t A141489 Select[Range[0,200],PrimeQ[#^2+#+257]&] (* _Harvey P. Dale_, Jun 07 2016 *) %o A141489 (Magma) [n: n in [0..5000] |IsPrime(n^2+n+257)]; // _Vincenzo Librandi_, Nov 25 2010 %o A141489 (PARI) isok(n) = isprime(n^2+n+257); \\ _Michel Marcus_, Mar 12 2017 %Y A141489 Cf. A002837, A056561, A133157, A133160. %K A141489 nonn %O A141489 1,2 %A A141489 _Parthasarathy Nambi_, Aug 09 2008 %E A141489 More terms from _Vincenzo Librandi_, Mar 25 2010