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 A089238 #11 Aug 10 2025 20:52:11 %S A089238 2,4,6,10,14,16,20,24,26,34,40,44,54,56,60,64,70,76,86,90,104,110,116, %T A089238 120,124,126,130,136,140,146,150,154,164,166,174,186,194,200,204,230, %U A089238 240,244,260,264,286,300,306,336,346,354,374,386,394,400,414,416,420 %N A089238 Numbers k such that 3*k^2/2 - 1 is a prime. %C A089238 All terms must be even numbers. - _Harvey P. Dale_, Jul 03 2017 %D A089238 M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988 %D A089238 Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta,UTET, CittaStudiEdizioni, Milano 1997 %t A089238 Select[Range[0,500,2],PrimeQ[(3#^2)/2-1]&] (* _Harvey P. Dale_, Jul 03 2017 *) %o A089238 (PARI) forstep(n=2,1000,2, if(isprime(3*n^2/2-1), print1(n,", "))) - _Rick L. Shepherd_, May 06 2008 %Y A089238 Cf. A090686. %K A089238 nonn %O A089238 1,1 %A A089238 _Giovanni Teofilatto_, Dec 22 2003 %E A089238 Corrected and extended by _Rick L. Shepherd_, May 06 2008