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 A193807 #11 Aug 19 2019 03:17:46
%S A193807 1,1,2,1,6,1,2,3,2,1,6,1,2,3,2,1,6,1,8,3,4,1,6,2,2,6,2,1,12,1,6,6,8,2,
%T A193807 24,1,2,9,2,1,30,1,2,3,2,1,6,2,2,6,10,1,24,3,4,6,2,1,30,1,4,9,4,2,6,1,
%U A193807 2,3,2,1,6,1,2,12,4,4,36,1,2,9,4,1,12
%N A193807 Smallest positive integer k such that n*k^2 + 1 is a prime.
%H A193807 Amiram Eldar, <a href="/A193807/b193807.txt">Table of n, a(n) for n = 1..10000</a>
%e A193807 a(5) = 6 because 5*6^2 + 1 = 181 is prime.
%t A193807 Table[k = 0; While[!PrimeQ[n*k^2 + 1], k++]; k, {n, 110}]
%o A193807 (PARI) a(n) = my(k=1); while (!isprime(n*k^2 + 1), k++); k; \\ _Michel Marcus_, Aug 19 2019
%K A193807 nonn
%O A193807 1,3
%A A193807 _Michel Lagneau_, Aug 05 2011