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 A358878 #24 Apr 02 2023 10:27:36 %S A358878 2,5,7,15,20,47,84,138,169,257,263,431,559,2939,4403,4870,5273 %N A358878 Numbers k such that k! + (k!/2) - 1 is prime. %C A358878 Numbers k such that A070960(k) - 1 is prime. %C A358878 No more terms < 10000. - _Vaclav Kotesovec_, Dec 12 2022 %o A358878 (PARI) is(k) = isprime(k!+(k!/2)-1); %Y A358878 Cf. A070960, A358805. %K A358878 nonn,more %O A358878 1,1 %A A358878 _Arsen Vardanyan_, Dec 04 2022 %E A358878 a(14)-a(17) from _Vaclav Kotesovec_, Dec 07 2022