cp's OEIS Frontend

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.

A359180 Numbers k such that k!^2 / 2 + 1 is prime.

This page as a plain text file.
%I A359180 #31 Apr 11 2023 03:47:30
%S A359180 2,3,6,18,19,82,1298,3139,3687,4637
%N A359180 Numbers k such that k!^2 / 2 + 1 is prime.
%e A359180 3!^2 / 2 + 1 = 6^2/2 + 1 = 19, a prime number, so 3 is a term.
%o A359180 (PARI) isok(k) = (k>1) && isprime(k!^2 / 2 + 1); \\ _Michel Marcus_, Jan 15 2023
%Y A359180 Cf. A002981, A046029, A358805, A358878.
%K A359180 nonn,hard,more
%O A359180 1,1
%A A359180 _Arsen Vardanyan_, Dec 18 2022
%E A359180 a(7) from _Michael S. Branicky_, Dec 18 2022
%E A359180 a(8)-a(10) from _Michael S. Branicky_, Apr 10 2023