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 A224718 #7 Apr 17 2013 13:24:44 %S A224718 7,41,43,107,157,193,239,251,257,293,307,443,457,557,577,593,607,643, %T A224718 743,757,829,857,907,1093,1193,1303,1307,1451,1483,1493,1543,1607, %U A224718 1657,1693,1723,1789,1907,1993,2143,2207,2243,2267,2293,2309,2357,2393,2543 %N A224718 Primes p such that p^2 + 1 is not squarefree. %H A224718 Zak Seidov, <a href="/A224718/b224718.txt">Table of n, a(n) for n = 1..1000</a> %e A224718 7^2 + 1 = 50 = 2*5^2, 41^2 + 1 = 1681 = 2*29^2. %t A224718 Select[Prime[Range[300]], ! SquareFreeQ[#^2 + 1] &] %Y A224718 Cf. A039787. %K A224718 nonn %O A224718 1,1 %A A224718 _Zak Seidov_, Apr 16 2013