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 A182091 #16 Sep 08 2022 08:45:54 %S A182091 4,6,8,10,13,17,18,21,22,25,30,34,36,38,41,42,45,46,56,57,58,62,64,69, %T A182091 70,72,74,86,88,101,105,113,114,116,120,122,126,132,133,141,157,158, %U A182091 174,176,181,182,186,192,198,200,205,216,217,221,224,240,253,254 %N A182091 Numbers n such that (n-1)*n^2/2-1 is prime. %H A182091 G. C. Greubel, <a href="/A182091/b182091.txt">Table of n, a(n) for n = 1..5000</a> %e A182091 a(1)=4 because (4-1)*4^2/2-1=23 is prime, a(2)=6 because (6-1)*6^2/2-1=89 is prime. %t A182091 Select[Range[300], PrimeQ[(# - 1)*#^2/2 - 1] &] (* _T. D. Noe_, Apr 11 2012 *) %o A182091 (PARI) is(n)=isprime((n-1)*n^2/2-1) \\ _Charles R Greathouse IV_, Jun 13 2017 %o A182091 (Magma) [n: n in [1..300] |IsPrime((n-1)*n^2 div 2-1)]; // _Vincenzo Librandi_, Aug 21 2017 %Y A182091 Cf. A006002. %K A182091 nonn,easy %O A182091 1,1 %A A182091 _Gerasimov Sergey_, Apr 11 2012