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Primes p such that p^2 + 1 is not squarefree.
3

%I #7 Apr 17 2013 13:24:44

%S 7,41,43,107,157,193,239,251,257,293,307,443,457,557,577,593,607,643,

%T 743,757,829,857,907,1093,1193,1303,1307,1451,1483,1493,1543,1607,

%U 1657,1693,1723,1789,1907,1993,2143,2207,2243,2267,2293,2309,2357,2393,2543

%N Primes p such that p^2 + 1 is not squarefree.

%H Zak Seidov, <a href="/A224718/b224718.txt">Table of n, a(n) for n = 1..1000</a>

%e 7^2 + 1 = 50 = 2*5^2, 41^2 + 1 = 1681 = 2*29^2.

%t Select[Prime[Range[300]], ! SquareFreeQ[#^2 + 1] &]

%Y Cf. A039787.

%K nonn

%O 1,1

%A _Zak Seidov_, Apr 16 2013