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 A099350 #27 Jul 12 2024 01:14:02 %S A099350 0,1,2,3,5,6,10,11,51,63,197,313,579,1264,2276,2669,4316,4382,4678, %T A099350 7907,10843 %N A099350 Numbers k such that 4*k! - 1 is prime. %C A099350 a(19) > 4570. - _Jinyuan Wang_, Feb 04 2020 %e A099350 k = 5 is here because 4*5! - 1 = 479 is prime. %p A099350 for n from 0 to 1000 do if isprime(4*n! - 1) then print(n) end if end do; %t A099350 For[n = 0, True, n++, If[PrimeQ[4 n! - 1], Print[n]]] (* _Jean-François Alcover_, Sep 23 2015 *) %o A099350 (PARI) is_A099350(n)=ispseudoprime(n!*4-1) \\ _M. F. Hasler_, Sep 20 2015 %Y A099350 Cf. A076680. %Y A099350 Cf. A002982, A076133, A076134, A099351, A180627, A180628, A180629, A180630, A180631. %K A099350 nonn,hard,more %O A099350 1,3 %A A099350 _Brian Kell_, Oct 12 2004 %E A099350 a(14) from _Alois P. Heinz_, Sep 21 2015 %E A099350 a(15)-a(16) from _Jean-François Alcover_, Sep 23 2015 %E A099350 a(17)-a(18) from _Jinyuan Wang_, Feb 04 2020 %E A099350 a(19) from _Michael S. Branicky_, May 16 2023 %E A099350 a(20)-a(21) from _Michael S. Branicky_, Jul 11 2024